diff --git a/bypy/macos/__main__.py b/bypy/macos/__main__.py
index 3627540407..497ea0828f 100644
--- a/bypy/macos/__main__.py
+++ b/bypy/macos/__main__.py
@@ -810,7 +810,8 @@ def main(args, ext_dir, test_runner):
     build_dir = abspath(join(mkdtemp('frozen-'), APPNAME + '.app'))
     inc_dir = abspath(mkdtemp('include'))
     if args.skip_tests:
-        test_runner = lambda *a: None
+        def test_runner(*a):
+            return None
     Freeze(build_dir, ext_dir, inc_dir, test_runner, dont_strip=args.dont_strip, sign_installers=args.sign_installers, notarize=args.notarize)
 
 
diff --git a/setup/linux-installer.py b/setup/linux-installer.py
index 26ad07c26c..a7a4c1b4ce 100644
--- a/setup/linux-installer.py
+++ b/setup/linux-installer.py
@@ -40,7 +40,8 @@ if py3:
     from urllib.parse import urlparse
     from urllib.request import BaseHandler, build_opener, Request, urlopen, getproxies, addinfourl
     import http.client as httplib
-    encode_for_subprocess = lambda x: x
+    def encode_for_subprocess(x):
+        return x
 else:
     from future_builtins import map
     from urlparse import urlparse
diff --git a/setup/plugins_mirror.py b/setup/plugins_mirror.py
index ea580e78bf..53b7c0cb24 100644
--- a/setup/plugins_mirror.py
+++ b/setup/plugins_mirror.py
@@ -156,7 +156,8 @@ def load_plugins_index():
 
 def convert_node(fields, x, names={}, import_data=None):
     name = x.__class__.__name__
-    conv = lambda x:convert_node(fields, x, names=names, import_data=import_data)
+    def conv(x):
+        return convert_node(fields, x, names=names, import_data=import_data)
     if name == 'Str':
         return x.s.decode('utf-8') if isinstance(x.s, bytes) else x.s
     elif name == 'Num':
diff --git a/src/calibre/__init__.py b/src/calibre/__init__.py
index bea87b67ef..8be1057beb 100644
--- a/src/calibre/__init__.py
+++ b/src/calibre/__init__.py
@@ -77,7 +77,8 @@ def to_unicode(raw, encoding='utf-8', errors='strict'):
 
 def patheq(p1, p2):
     p = os.path
-    d = lambda x : p.normcase(p.normpath(p.realpath(p.normpath(x))))
+    def d(x):
+        return p.normcase(p.normpath(p.realpath(p.normpath(x))))
     if not p1 or not p2:
         return False
     return d(p1) == d(p2)
diff --git a/src/calibre/customize/__init__.py b/src/calibre/customize/__init__.py
index d92d29ba64..0863226e05 100644
--- a/src/calibre/customize/__init__.py
+++ b/src/calibre/customize/__init__.py
@@ -552,7 +552,7 @@ class CatalogPlugin(Plugin):  # {{{
         from calibre.customize.ui import config
         from calibre.ptempfile import PersistentTemporaryDirectory
 
-        if not type(self) in builtin_plugins and self.name not in config['disabled_plugins']:
+        if type(self) not in builtin_plugins and self.name not in config['disabled_plugins']:
             files_to_copy = [f"{self.name.lower()}.{ext}" for ext in ["ui","py"]]
             resources = zipfile.ZipFile(self.plugin_path,'r')
 
diff --git a/src/calibre/customize/ui.py b/src/calibre/customize/ui.py
index 1378237326..3d77efd9d2 100644
--- a/src/calibre/customize/ui.py
+++ b/src/calibre/customize/ui.py
@@ -180,7 +180,8 @@ def _run_filetype_plugins(path_to_file, ft=None, occasion='preprocess'):
                 print('Running file type plugin %s failed with traceback:'%plugin.name, file=oe)
                 traceback.print_exc(file=oe)
         sys.stdout, sys.stderr = oo, oe
-    x = lambda j: os.path.normpath(os.path.normcase(j))
+    def x(j):
+        return os.path.normpath(os.path.normcase(j))
     if occasion == 'postprocess' and x(nfp) != x(path_to_file):
         shutil.copyfile(nfp, path_to_file)
         nfp = path_to_file
diff --git a/src/calibre/db/adding.py b/src/calibre/db/adding.py
index 3b14633078..372b19e936 100644
--- a/src/calibre/db/adding.py
+++ b/src/calibre/db/adding.py
@@ -41,18 +41,23 @@ def compile_rule(rule):
     if 'with' in mt:
         q = icu_lower(rule['query'])
         if 'startswith' in mt:
-            func = lambda filename: icu_lower(filename).startswith(q)
+            def func(filename):
+                return icu_lower(filename).startswith(q)
         else:
-            func = lambda filename: icu_lower(filename).endswith(q)
+            def func(filename):
+                return icu_lower(filename).endswith(q)
     elif 'glob' in mt:
         q = compile_glob(rule['query'])
-        func  = lambda filename: q.match(filename) is not None
+        def func(filename):
+            return (q.match(filename) is not None)
     else:
         q = re.compile(rule['query'])
-        func  = lambda filename: q.match(filename) is not None
+        def func(filename):
+            return (q.match(filename) is not None)
     ans = func
     if mt.startswith('not_'):
-        ans = lambda filename: not func(filename)
+        def ans(filename):
+            return (not func(filename))
     return ans, rule['action'] == 'add'
 
 
diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index 12d82963b7..0cd4a35db3 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -1262,7 +1262,8 @@ class DB:
         import codecs
         from apsw import Shell
         if callback is None:
-            callback = lambda x: x
+            def callback(x):
+                return x
         uv = int(self.user_version)
 
         with TemporaryFile(suffix='.sql') as fname:
@@ -1587,7 +1588,8 @@ class DB:
     def compress_covers(self, path_map, jpeg_quality, progress_callback):
         cpath_map = {}
         if not progress_callback:
-            progress_callback = lambda book_id, old_sz, new_sz: None
+            def progress_callback(book_id, old_sz, new_sz):
+                return None
         for book_id, path in path_map.items():
             path = os.path.abspath(os.path.join(self.library_path, path, 'cover.jpg'))
             try:
diff --git a/src/calibre/db/fields.py b/src/calibre/db/fields.py
index 5e0a947869..49da62475d 100644
--- a/src/calibre/db/fields.py
+++ b/src/calibre/db/fields.py
@@ -47,7 +47,8 @@ def numeric_sort_key(defval, x):
     return x if type(x) in (int, float) else defval
 
 
-IDENTITY = lambda x: x
+def IDENTITY(x):
+    return x
 
 
 class InvalidLinkTable(Exception):
diff --git a/src/calibre/db/lazy.py b/src/calibre/db/lazy.py
index 36040a6ec2..617c590ecf 100644
--- a/src/calibre/db/lazy.py
+++ b/src/calibre/db/lazy.py
@@ -223,7 +223,8 @@ def has_cover_getter(dbref, book_id, cache):
         return ret
 
 
-fmt_custom = lambda x:list(x) if isinstance(x, tuple) else x
+def fmt_custom(x):
+    return (list(x) if isinstance(x, tuple) else x)
 
 
 def custom_getter(field, dbref, book_id, cache):
diff --git a/src/calibre/db/legacy.py b/src/calibre/db/legacy.py
index a17e15ab85..7567050030 100644
--- a/src/calibre/db/legacy.py
+++ b/src/calibre/db/legacy.py
@@ -181,7 +181,8 @@ class LibraryDatabase:
 
         self.is_second_db = is_second_db
         if progress_callback is None:
-            progress_callback = lambda x, y:True
+            def progress_callback(x, y):
+                return True
         self.listeners = set()
 
         backend = self.backend = create_backend(library_path, default_prefs=default_prefs,
diff --git a/src/calibre/db/search.py b/src/calibre/db/search.py
index f4b8e8da41..8e7b4b106d 100644
--- a/src/calibre/db/search.py
+++ b/src/calibre/db/search.py
@@ -237,9 +237,11 @@ class NumericSearch:  # {{{
         dt = datatype
 
         if is_many and query in {'true', 'false'}:
-            valcheck = lambda x: True
+            def valcheck(x):
+                return True
             if datatype == 'rating':
-                valcheck = lambda x: x is not None and x > 0
+                def valcheck(x):
+                    return (x is not None and x > 0)
             found = set()
             for val, book_ids in field_iter():
                 if valcheck(val):
@@ -248,14 +250,18 @@ class NumericSearch:  # {{{
 
         if query == 'false':
             if location == 'cover':
-                relop = lambda x,y: not bool(x)
+                def relop(x, y):
+                    return (not bool(x))
             else:
-                relop = lambda x,y: x is None
+                def relop(x, y):
+                    return (x is None)
         elif query == 'true':
             if location == 'cover':
-                relop = lambda x,y: bool(x)
+                def relop(x, y):
+                    return bool(x)
             else:
-                relop = lambda x,y: x is not None
+                def relop(x, y):
+                    return (x is not None)
         else:
             for k, relop in iteritems(self.operators):
                 if query.startswith(k):
@@ -265,8 +271,10 @@ class NumericSearch:  # {{{
                 relop = self.operators['=']
 
             if dt == 'rating':
-                cast = lambda x: 0 if x is None else int(x)
-                adjust = lambda x: x // 2
+                def cast(x):
+                    return (0 if x is None else int(x))
+                def adjust(x):
+                    return (x // 2)
             else:
                 # Datatype is empty if the source is a template. Assume float
                 cast = float if dt in ('float', 'composite', 'half-rating', '') else int
diff --git a/src/calibre/db/tests/filesystem.py b/src/calibre/db/tests/filesystem.py
index e0703c1d19..363aa5af5c 100644
--- a/src/calibre/db/tests/filesystem.py
+++ b/src/calibre/db/tests/filesystem.py
@@ -186,7 +186,8 @@ class FilesystemTest(BaseTest):
 
     def test_find_books_in_directory(self):
         from calibre.db.adding import find_books_in_directory, compile_rule
-        strip = lambda files: frozenset({os.path.basename(x) for x in files})
+        def strip(files):
+            return frozenset({os.path.basename(x) for x in files})
 
         def q(one, two):
             one, two = {strip(a) for a in one}, {strip(b) for b in two}
diff --git a/src/calibre/db/tests/legacy.py b/src/calibre/db/tests/legacy.py
index b6dee63e4e..194f682b23 100644
--- a/src/calibre/db/tests/legacy.py
+++ b/src/calibre/db/tests/legacy.py
@@ -57,7 +57,8 @@ def run_funcs(self, db, ndb, funcs):
         if callable(meth):
             meth(*args)
         else:
-            fmt = lambda x:x
+            def fmt(x):
+                return x
             if meth[0] in {'!', '@', '#', '+', '$', '-', '%'}:
                 if meth[0] != '+':
                     fmt = {'!':dict, '@':lambda x:frozenset(x or ()), '#':lambda x:set((x or '').split(',')),
@@ -256,12 +257,14 @@ class LegacyTest(BaseTest):
             'books_in_series_of':[(0,), (1,), (2,)],
             'books_with_same_title':[(Metadata(db.title(0)),), (Metadata(db.title(1)),), (Metadata('1234'),)],
         }):
-            fmt = lambda x: x
+            def fmt(x):
+                return x
             if meth[0] in {'!', '@'}:
                 fmt = {'!':dict, '@':frozenset}[meth[0]]
                 meth = meth[1:]
             elif meth == 'get_authors_with_ids':
-                fmt = lambda val:{x[0]:tuple(x[1:]) for x in val}
+                def fmt(val):
+                    return {x[0]: tuple(x[1:]) for x in val}
             for a in args:
                 self.assertEqual(fmt(getattr(db, meth)(*a)), fmt(getattr(ndb, meth)(*a)),
                                  f'The method: {meth}() returned different results for argument {a}')
diff --git a/src/calibre/db/tests/reading.py b/src/calibre/db/tests/reading.py
index 8dc85f4c66..907844d0c8 100644
--- a/src/calibre/db/tests/reading.py
+++ b/src/calibre/db/tests/reading.py
@@ -612,9 +612,11 @@ class ReadingTest(BaseTest):
             self.assertSetEqual(set(mi.custom_field_keys()), set(pmi.custom_field_keys()))
 
             for field in STANDARD_METADATA_FIELDS | {'#series_index'}:
-                f = lambda x: x
+                def f(x):
+                    return x
                 if field == 'formats':
-                    f = lambda x: x if x is None else tuple(x)
+                    def f(x):
+                        return (x if x is None else tuple(x))
                 self.assertEqual(f(getattr(mi, field)), f(getattr(pmi, field)),
                                 f'Standard field: {field} not the same for book {book_id}')
                 self.assertEqual(mi.format_field(field), pmi.format_field(field),
diff --git a/src/calibre/db/tests/writing.py b/src/calibre/db/tests/writing.py
index 014a1eb970..5dbfe5c2ef 100644
--- a/src/calibre/db/tests/writing.py
+++ b/src/calibre/db/tests/writing.py
@@ -23,20 +23,23 @@ class WritingTest(BaseTest):
     def create_getter(self, name, getter=None):
         if getter is None:
             if name.endswith('_index'):
-                ans = lambda db:partial(db.get_custom_extra, index_is_id=True,
-                                        label=name[1:].replace('_index', ''))
+                def ans(db):
+                    return partial(db.get_custom_extra, index_is_id=True, label=name[1:].replace('_index', ''))
             else:
-                ans = lambda db:partial(db.get_custom, label=name[1:],
-                                       index_is_id=True)
+                def ans(db):
+                    return partial(db.get_custom, label=name[1:], index_is_id=True)
         else:
-            ans = lambda db:partial(getattr(db, getter), index_is_id=True)
+            def ans(db):
+                return partial(getattr(db, getter), index_is_id=True)
         return ans
 
     def create_setter(self, name, setter=None):
         if setter is None:
-            ans = lambda db:partial(db.set_custom, label=name[1:], commit=True)
+            def ans(db):
+                return partial(db.set_custom, label=name[1:], commit=True)
         else:
-            ans = lambda db:partial(getattr(db, setter), commit=True)
+            def ans(db):
+                return partial(getattr(db, setter), commit=True)
         return ans
 
     def create_test(self, name, vals, getter=None, setter=None):
diff --git a/src/calibre/db/utils.py b/src/calibre/db/utils.py
index 2ac8a0e0a8..04dbc96ea5 100644
--- a/src/calibre/db/utils.py
+++ b/src/calibre/db/utils.py
@@ -408,7 +408,8 @@ def atof(string):
 
 def type_safe_sort_key_function(keyfunc=None):
     if keyfunc is None:
-        keyfunc = lambda x: x
+        def keyfunc(x):
+            return x
     sentinel = object()
     first_value = sentinel
 
diff --git a/src/calibre/db/write.py b/src/calibre/db/write.py
index 21965fab39..5f97dd80ce 100644
--- a/src/calibre/db/write.py
+++ b/src/calibre/db/write.py
@@ -164,11 +164,13 @@ def get_adapter(name, metadata):
     elif dt == 'comments':
         ans = single_text
     elif dt == 'rating':
-        ans = lambda x: None if x in {None, 0} else min(10, max(0, adapt_number(int, x)))
+        def ans(x):
+            return (None if x in {None, 0} else min(10, max(0, adapt_number(int, x))))
     elif dt == 'enumeration':
         ans = single_text
     elif dt == 'composite':
-        ans = lambda x: x
+        def ans(x):
+            return x
 
     if name == 'title':
         return lambda x: ans(x) or _('Unknown')
diff --git a/src/calibre/devices/android/driver.py b/src/calibre/devices/android/driver.py
index 268b2c3663..facd064009 100644
--- a/src/calibre/devices/android/driver.py
+++ b/src/calibre/devices/android/driver.py
@@ -48,7 +48,6 @@ class ANDROID(USBMS):
                        0x0cf5 : HTC_BCDS,
                        0x2910 : HTC_BCDS,
                        0xe77  : HTC_BCDS,
-                       0xff9  : HTC_BCDS,
                        0x0001 : [0x255],
             },
 
diff --git a/src/calibre/ebooks/chardet.py b/src/calibre/ebooks/chardet.py
index afa0d9b4d8..01bc822dda 100644
--- a/src/calibre/ebooks/chardet.py
+++ b/src/calibre/ebooks/chardet.py
@@ -45,9 +45,11 @@ def strip_encoding_declarations(raw, limit=50*1024, preserve_newlines=False):
     is_binary = isinstance(raw, bytes)
     if preserve_newlines:
         if is_binary:
-            sub = lambda m: b'\n' * m.group().count(b'\n')
+            def sub(m):
+                return (b'\n' * m.group().count(b'\n'))
         else:
-            sub = lambda m: '\n' * m.group().count('\n')
+            def sub(m):
+                return ('\n' * m.group().count('\n'))
     else:
         sub = b'' if is_binary else ''
     for pat in lazy_encoding_pats(is_binary):
diff --git a/src/calibre/ebooks/comic/input.py b/src/calibre/ebooks/comic/input.py
index 1881916c89..5728f6699b 100644
--- a/src/calibre/ebooks/comic/input.py
+++ b/src/calibre/ebooks/comic/input.py
@@ -63,9 +63,11 @@ def find_pages(dir, sort_on_mtime=False, verbose=False):
     # levels, in which case simply use the filenames.
     basename = os.path.basename if len(sep_counts) > 1 else lambda x: x
     if sort_on_mtime:
-        key = lambda x:os.stat(x).st_mtime
+        def key(x):
+            return os.stat(x).st_mtime
     else:
-        key = lambda x:numeric_sort_key(basename(x))
+        def key(x):
+            return numeric_sort_key(basename(x))
 
     pages.sort(key=key)
     if verbose:
diff --git a/src/calibre/ebooks/conversion/plugins/html_output.py b/src/calibre/ebooks/conversion/plugins/html_output.py
index 19fc47bd9c..1694ef29ef 100644
--- a/src/calibre/ebooks/conversion/plugins/html_output.py
+++ b/src/calibre/ebooks/conversion/plugins/html_output.py
@@ -193,7 +193,8 @@ class HTMLOutput(OutputFormatPlugin):
 
                 # render template
                 templite = Templite(template_html_data)
-                toc = lambda: self.generate_html_toc(oeb_book, path, output_dir)
+                def toc():
+                    return self.generate_html_toc(oeb_book, path, output_dir)
                 t = templite.render(ebookContent=ebook_content,
                         prevLink=prevLink, nextLink=nextLink,
                         has_toc=bool(oeb_book.toc.count()), toc=toc,
diff --git a/src/calibre/ebooks/djvu/djvubzzdec.py b/src/calibre/ebooks/djvu/djvubzzdec.py
index f5a0e9c06a..1e1e9eb3bd 100644
--- a/src/calibre/ebooks/djvu/djvubzzdec.py
+++ b/src/calibre/ebooks/djvu/djvubzzdec.py
@@ -500,8 +500,10 @@ class BZZDecoder():
         # Decode
         mtfno = 3
         markerpos = -1
-        zc = lambda i: self.zpcodec_decode(self.ctx, i)
-        dc = lambda i, bits: self.decode_binary(self.ctx, i, bits)
+        def zc(i):
+            return self.zpcodec_decode(self.ctx, i)
+        def dc(i, bits):
+            return self.decode_binary(self.ctx, i, bits)
         for i in range(self.xsize):
             ctxid = CTXIDS - 1
             if ctxid > mtfno:
diff --git a/src/calibre/ebooks/docx/fields.py b/src/calibre/ebooks/docx/fields.py
index a1da9b3fa5..95012eeb2c 100644
--- a/src/calibre/ebooks/docx/fields.py
+++ b/src/calibre/ebooks/docx/fields.py
@@ -247,7 +247,8 @@ def test_parse_fields(return_tests=False):
     class TestParseFields(unittest.TestCase):
 
         def test_hyperlink(self):
-            ae = lambda x, y: self.assertEqual(parse_hyperlink(x, None), y)
+            def ae(x, y):
+                return self.assertEqual(parse_hyperlink(x, None), y)
             ae(r'\l anchor1', {'anchor':'anchor1'})
             ae(r'www.calibre-ebook.com', {'url':'www.calibre-ebook.com'})
             ae(r'www.calibre-ebook.com \t target \o tt', {'url':'www.calibre-ebook.com', 'target':'target', 'title': 'tt'})
@@ -255,13 +256,15 @@ def test_parse_fields(return_tests=False):
             ae(r'xxxx \y yyyy', {'url': 'xxxx'})
 
         def test_xe(self):
-            ae = lambda x, y: self.assertEqual(parse_xe(x, None), y)
+            def ae(x, y):
+                return self.assertEqual(parse_xe(x, None), y)
             ae(r'"some name"', {'text':'some name'})
             ae(r'name \b \i', {'text':'name', 'bold':None, 'italic':None})
             ae(r'xxx \y a', {'text':'xxx', 'yomi':'a'})
 
         def test_index(self):
-            ae = lambda x, y: self.assertEqual(parse_index(x, None), y)
+            def ae(x, y):
+                return self.assertEqual(parse_index(x, None), y)
             ae(r'', {})
             ae(r'\b \c 1', {'bookmark':None, 'columns-per-page': '1'})
 
diff --git a/src/calibre/ebooks/docx/writer/styles.py b/src/calibre/ebooks/docx/writer/styles.py
index c91feb180a..b341475be4 100644
--- a/src/calibre/ebooks/docx/writer/styles.py
+++ b/src/calibre/ebooks/docx/writer/styles.py
@@ -64,7 +64,8 @@ class CombinedStyle:
 
     def serialize(self, styles, normal_style):
         makeelement = self.namespace.makeelement
-        w = lambda x: '{{{}}}{}'.format(self.namespace.namespaces['w'], x)
+        def w(x):
+            return '{{{}}}{}'.format(self.namespace.namespaces['w'], x)
         block = makeelement(styles, 'w:style', w_styleId=self.id, w_type='paragraph')
         makeelement(block, 'w:name', w_val=self.name)
         makeelement(block, 'w:qFormat')
diff --git a/src/calibre/ebooks/epub/cfi/parse.py b/src/calibre/ebooks/epub/cfi/parse.py
index e348098c11..e3ddc41de2 100644
--- a/src/calibre/ebooks/epub/cfi/parse.py
+++ b/src/calibre/ebooks/epub/cfi/parse.py
@@ -28,7 +28,8 @@ class Parser:
         # No leading zeros, except for numbers in (0, 1) and no trailing zeros for the fractional part
         frac = r'\.[0-9]*[1-9]'
         number = r'(?:[1-9][0-9]*(?:{0})?)|(?:0{0})|(?:0)'.format(frac)
-        c = lambda x:regex.compile(x, flags=regex.VERSION1)
+        def c(x):
+            return regex.compile(x, flags=regex.VERSION1)
 
         # A step of the form /integer
         self.step_pat = c(r'/(%s)' % integer)
diff --git a/src/calibre/ebooks/lrf/html/convert_from.py b/src/calibre/ebooks/lrf/html/convert_from.py
index 5748feed44..5f67b0ebf1 100644
--- a/src/calibre/ebooks/lrf/html/convert_from.py
+++ b/src/calibre/ebooks/lrf/html/convert_from.py
@@ -811,7 +811,8 @@ class HTMLConverter:
             for x, y in [('\xad', ''), ('\xa0', ' '), ('\ufb00', 'ff'), ('\ufb01', 'fi'), ('\ufb02', 'fl'), ('\ufb03', 'ffi'), ('\ufb04', 'ffl')]:
                 src = src.replace(x, y)
 
-            valigner = lambda x: x
+            def valigner(x):
+                return x
             if 'vertical-align' in css:
                 valign = css['vertical-align']
                 if valign in ('sup', 'super', 'sub'):
diff --git a/src/calibre/ebooks/metadata/book/base.py b/src/calibre/ebooks/metadata/book/base.py
index 2d14faf4ff..bc17b256f0 100644
--- a/src/calibre/ebooks/metadata/book/base.py
+++ b/src/calibre/ebooks/metadata/book/base.py
@@ -54,8 +54,10 @@ def reset_field_metadata():
     field_metadata = FieldMetadata()
 
 
-ck = lambda typ: icu_lower(typ).strip().replace(':', '').replace(',', '')
-cv = lambda val: val.strip().replace(',', '|')
+def ck(typ):
+    return icu_lower(typ).strip().replace(':', '').replace(',', '')
+def cv(val):
+    return val.strip().replace(',', '|')
 
 
 class Metadata:
diff --git a/src/calibre/ebooks/metadata/lrx.py b/src/calibre/ebooks/metadata/lrx.py
index 71d631cf02..809dd122f5 100644
--- a/src/calibre/ebooks/metadata/lrx.py
+++ b/src/calibre/ebooks/metadata/lrx.py
@@ -38,7 +38,8 @@ def short_be(buf):
 
 
 def get_metadata(f):
-    read = lambda at, amount: _read(f, at, amount)
+    def read(at, amount):
+        return _read(f, at, amount)
     f.seek(0)
     buf = f.read(12)
     if buf[4:] == b'ftypLRX2':
diff --git a/src/calibre/ebooks/metadata/opf2.py b/src/calibre/ebooks/metadata/opf2.py
index 4b84705628..ce3eb80a4c 100644
--- a/src/calibre/ebooks/metadata/opf2.py
+++ b/src/calibre/ebooks/metadata/opf2.py
@@ -1652,7 +1652,8 @@ def metadata_to_opf(mi, as_string=True, default_lang=None):
     if mi.tags:
         for tag in mi.tags:
             factory(DC('subject'), tag)
-    meta = lambda n, c: factory('meta', name='calibre:'+n, content=c)
+    def meta(n, c):
+        return factory('meta', name='calibre:' + n, content=c)
     if getattr(mi, 'author_link_map', None) is not None:
         meta('author_link_map', dump_dict(mi.author_link_map))
     if mi.series:
diff --git a/src/calibre/ebooks/metadata/rb.py b/src/calibre/ebooks/metadata/rb.py
index bdca8a7c0f..4140ab3c55 100644
--- a/src/calibre/ebooks/metadata/rb.py
+++ b/src/calibre/ebooks/metadata/rb.py
@@ -21,7 +21,8 @@ def get_metadata(stream):
             return mi
         stream.read(10)
 
-        read_i32 = lambda: struct.unpack('<I', stream.read(4))[0]
+        def read_i32():
+            return struct.unpack('<I', stream.read(4))[0]
 
         stream.seek(read_i32())
         toc_count = read_i32()
diff --git a/src/calibre/ebooks/metadata/sources/amazon.py b/src/calibre/ebooks/metadata/sources/amazon.py
index 8d9580aa2a..3594495184 100644
--- a/src/calibre/ebooks/metadata/sources/amazon.py
+++ b/src/calibre/ebooks/metadata/sources/amazon.py
@@ -96,7 +96,8 @@ def parse_details_page(url, log, timeout, browser, domain):
         from calibre.ebooks.metadata.sources.update import search_engines_module
         get_data_for_cached_url = search_engines_module().get_data_for_cached_url
     except Exception:
-        get_data_for_cached_url = lambda *a: None
+        def get_data_for_cached_url(*a):
+            return None
     raw = get_data_for_cached_url(url)
     if raw:
         log('Using cached details for url:', url)
diff --git a/src/calibre/ebooks/metadata/sources/identify.py b/src/calibre/ebooks/metadata/sources/identify.py
index 220eb4295b..1e13ce63a4 100644
--- a/src/calibre/ebooks/metadata/sources/identify.py
+++ b/src/calibre/ebooks/metadata/sources/identify.py
@@ -509,7 +509,8 @@ def identify(log, abort,  # {{{
         am_rules = compile_rules(am_rules)
 
     # normalize unicode strings
-    n = lambda x: unicodedata.normalize('NFC', as_unicode(x or '', errors='replace'))
+    def n(x):
+        return unicodedata.normalize('NFC', as_unicode(x or '', errors='replace'))
     for r in results:
         if r.tags:
             r.tags = list(map(n, r.tags))
diff --git a/src/calibre/ebooks/metadata/xmp.py b/src/calibre/ebooks/metadata/xmp.py
index 33a01c6eeb..17f8715665 100644
--- a/src/calibre/ebooks/metadata/xmp.py
+++ b/src/calibre/ebooks/metadata/xmp.py
@@ -542,7 +542,8 @@ def metadata_to_xmp_packet(mi):
 
 
 def find_used_namespaces(elem):
-    getns = lambda x: (x.partition('}')[0][1:] if '}' in x else None)
+    def getns(x):
+        return (x.partition('}')[0][1:] if '}' in x else None)
     ans = {getns(x) for x in list(elem.attrib) + [elem.tag]}
     for child in elem.iterchildren(etree.Element):
         ans |= find_used_namespaces(child)
diff --git a/src/calibre/ebooks/mobi/debug/mobi8.py b/src/calibre/ebooks/mobi/debug/mobi8.py
index f7c1cc0df5..928cae3589 100644
--- a/src/calibre/ebooks/mobi/debug/mobi8.py
+++ b/src/calibre/ebooks/mobi/debug/mobi8.py
@@ -37,7 +37,8 @@ class FDST:
 
     def __str__(self):
         ans = ['FDST record']
-        a = lambda k, v:ans.append('%s: %s'%(k, v))
+        def a(k, v):
+            return ans.append('%s: %s' % (k, v))
         a('Offset to sections', self.sec_off)
         a('Number of section records', self.num_sections)
         ans.append('**** %d Sections ****'% len(self.sections))
diff --git a/src/calibre/ebooks/mobi/reader/mobi6.py b/src/calibre/ebooks/mobi/reader/mobi6.py
index 407e6e1c12..8a90046b08 100644
--- a/src/calibre/ebooks/mobi/reader/mobi6.py
+++ b/src/calibre/ebooks/mobi/reader/mobi6.py
@@ -823,7 +823,8 @@ class MobiReader:
             unpack = decompress_doc
 
         elif self.book_header.compression_type == b'\x00\x01':
-            unpack = lambda x: x
+            def unpack(x):
+                return x
         else:
             raise MobiError('Unknown compression algorithm: %r' % self.book_header.compression_type)
         self.mobi_html = b''.join(map(unpack, text_sections))
diff --git a/src/calibre/ebooks/mobi/utils.py b/src/calibre/ebooks/mobi/utils.py
index 66982233fc..069a226b2e 100644
--- a/src/calibre/ebooks/mobi/utils.py
+++ b/src/calibre/ebooks/mobi/utils.py
@@ -640,6 +640,7 @@ def convert_color_for_font_tag(val):
     rgba = parse_color_string(str(val or ''))
     if rgba is None or rgba == 'currentColor':
         return str(val)
-    clamp = lambda x: min(x, max(0, x), 1)
+    def clamp(x):
+        return min(x, max(0, x), 1)
     rgb = map(clamp, rgba[:3])
     return '#' + ''.join(map(lambda x:'%02x' % int(x * 255), rgb))
diff --git a/src/calibre/ebooks/mobi/writer8/header.py b/src/calibre/ebooks/mobi/writer8/header.py
index 33fe8ffcf4..cc539a60f6 100644
--- a/src/calibre/ebooks/mobi/writer8/header.py
+++ b/src/calibre/ebooks/mobi/writer8/header.py
@@ -14,9 +14,12 @@ from calibre.ebooks.mobi.utils import align_block
 from polyglot.builtins import iteritems, as_bytes
 
 NULL = 0xffffffff
-zeroes = lambda x: b'\0'*x
-nulls = lambda x: b'\xff'*x
-short = lambda x: pack(b'>H', x)
+def zeroes(x):
+    return (b'\x00' * x)
+def nulls(x):
+    return (b'\xff' * x)
+def short(x):
+    return pack(b'>H', x)
 
 
 class Header(OrderedDict):
diff --git a/src/calibre/ebooks/mobi/writer8/index.py b/src/calibre/ebooks/mobi/writer8/index.py
index b56eb02774..ef20c8966d 100644
--- a/src/calibre/ebooks/mobi/writer8/index.py
+++ b/src/calibre/ebooks/mobi/writer8/index.py
@@ -13,7 +13,8 @@ from calibre.ebooks.mobi.writer8.header import Header
 
 TagMeta_ = namedtuple('TagMeta',
         'name number values_per_entry bitmask end_flag')
-TagMeta = lambda x:TagMeta_(*x)
+def TagMeta(x):
+    return TagMeta_(*x)
 EndTagTable = TagMeta(('eof', 0, 0, 0, 1))
 
 # map of mask to number of shifts needed, works with 1 bit and two-bit wide masks
diff --git a/src/calibre/ebooks/oeb/polish/main.py b/src/calibre/ebooks/oeb/polish/main.py
index 43fac8ed43..d445a959e0 100644
--- a/src/calibre/ebooks/oeb/polish/main.py
+++ b/src/calibre/ebooks/oeb/polish/main.py
@@ -161,7 +161,8 @@ def update_metadata(ebook, new_opf):
 
 
 def polish_one(ebook, opts, report, customization=None):
-    rt = lambda x: report('\n### ' + x)
+    def rt(x):
+        return report('\n### ' + x)
     jacket = None
     changed = False
     customization = customization or CUSTOMIZATION.copy()
diff --git a/src/calibre/ebooks/oeb/polish/utils.py b/src/calibre/ebooks/oeb/polish/utils.py
index d2dd7e916d..955237ce07 100644
--- a/src/calibre/ebooks/oeb/polish/utils.py
+++ b/src/calibre/ebooks/oeb/polish/utils.py
@@ -248,7 +248,8 @@ def apply_func_to_match_groups(match, func=icu_upper, handle_entities=handle_ent
     found_groups = False
     i = 0
     parts, pos = [], match.start()
-    f = lambda text:handle_entities(text, func)
+    def f(text):
+        return handle_entities(text, func)
     while True:
         i += 1
         try:
@@ -268,7 +269,8 @@ def apply_func_to_match_groups(match, func=icu_upper, handle_entities=handle_ent
 
 def apply_func_to_html_text(match, func=icu_upper, handle_entities=handle_entities):
     ''' Apply the specified function only to text between HTML tag definitions. '''
-    f = lambda text:handle_entities(text, func)
+    def f(text):
+        return handle_entities(text, func)
     parts = re.split(r'(<[^>]+>)', match.group())
     parts = (x if x.startswith('<') else f(x) for x in parts)
     return ''.join(parts)
diff --git a/src/calibre/ebooks/rtf2xml/paragraph_def.py b/src/calibre/ebooks/rtf2xml/paragraph_def.py
index 53407eb433..acb2281a05 100644
--- a/src/calibre/ebooks/rtf2xml/paragraph_def.py
+++ b/src/calibre/ebooks/rtf2xml/paragraph_def.py
@@ -116,8 +116,6 @@ if another paragraph_def is found, the state changes to collect_tokens.
         'sect-note_'    : 'endnotes-in-section',
         # list=> ls
         'list-text_'    : 'list-text',
-        # this line must be wrong because it duplicates an earlier one
-        'list-text_'    : 'list-text',
         'list______'    : 'list',
         'list-lev-d'    : 'list-level-definition',
         'list-cardi'    : 'list-cardinal-numbering',
diff --git a/src/calibre/ebooks/rtf2xml/tokenize.py b/src/calibre/ebooks/rtf2xml/tokenize.py
index d19f3ef61f..fcd2fb3dd2 100644
--- a/src/calibre/ebooks/rtf2xml/tokenize.py
+++ b/src/calibre/ebooks/rtf2xml/tokenize.py
@@ -136,7 +136,6 @@ class Tokenize:
             "&": "&amp;",
             "<": "&lt;",
             ">": "&gt;",
-            "\\~": "\\~ ",
             "\\_": "\\_ ",
             "\\:": "\\: ",
             "\\-": "\\- ",
diff --git a/src/calibre/gui2/device_drivers/configwidget.py b/src/calibre/gui2/device_drivers/configwidget.py
index 8f16f01ad0..6bad19f38c 100644
--- a/src/calibre/gui2/device_drivers/configwidget.py
+++ b/src/calibre/gui2/device_drivers/configwidget.py
@@ -70,11 +70,15 @@ class ConfigWidget(QWidget, Ui_ConfigWidget):
             if isinstance(extra_customization_message, list):
                 self.opt_extra_customization = []
                 if len(extra_customization_message) > 6:
-                    row_func = lambda x, y: ((x//2) * 2) + y
-                    col_func = lambda x: x%2
+                    def row_func(x, y):
+                        return (x // 2 * 2 + y)
+                    def col_func(x):
+                        return (x % 2)
                 else:
-                    row_func = lambda x, y: x*2 + y
-                    col_func = lambda x: 0
+                    def row_func(x, y):
+                        return (x * 2 + y)
+                    def col_func(x):
+                        return 0
 
                 for i, m in enumerate(extra_customization_message):
                     label_text, tt = parse_msg(m)
diff --git a/src/calibre/gui2/device_drivers/tabbed_device_config.py b/src/calibre/gui2/device_drivers/tabbed_device_config.py
index 6a87f0da62..5e3789ee3b 100644
--- a/src/calibre/gui2/device_drivers/tabbed_device_config.py
+++ b/src/calibre/gui2/device_drivers/tabbed_device_config.py
@@ -274,11 +274,15 @@ class ExtraCustomization(DeviceConfigTab):  # {{{
             if isinstance(extra_customization_message, list):
                 self.opt_extra_customization = []
                 if len(extra_customization_message) > 6:
-                    row_func = lambda x, y: ((x//2) * 2) + y
-                    col_func = lambda x: x%2
+                    def row_func(x, y):
+                        return (x // 2 * 2 + y)
+                    def col_func(x):
+                        return (x % 2)
                 else:
-                    row_func = lambda x, y: x*2 + y
-                    col_func = lambda x: 0
+                    def row_func(x, y):
+                        return (x * 2 + y)
+                    def col_func(x):
+                        return 0
 
                 for i, m in enumerate(extra_customization_message):
                     label_text, tt = parse_msg(m)
diff --git a/src/calibre/gui2/dialogs/custom_recipes.py b/src/calibre/gui2/dialogs/custom_recipes.py
index 96909a9510..afca6b7470 100644
--- a/src/calibre/gui2/dialogs/custom_recipes.py
+++ b/src/calibre/gui2/dialogs/custom_recipes.py
@@ -567,7 +567,8 @@ class CustomRecipes(Dialog):
 
         l.addWidget(self.bb)
         self.list_actions = []
-        la = lambda *args:self.list_actions.append(args)
+        def la(*args):
+            return self.list_actions.append(args)
         la('plus.png', _('&New recipe'), _('Create a new recipe from scratch'), self.add_recipe)
         la('news.png', _('Customize &builtin recipe'), _('Customize a builtin news download source'), self.customize_recipe)
         la('document_open.png', _('Load recipe from &file'), _('Load a recipe from a file'), self.load_recipe)
diff --git a/src/calibre/gui2/icon_theme.py b/src/calibre/gui2/icon_theme.py
index ac989db981..ff2fca785c 100644
--- a/src/calibre/gui2/icon_theme.py
+++ b/src/calibre/gui2/icon_theme.py
@@ -127,7 +127,8 @@ def read_theme_from_folder(path):
             return int(x)
         except Exception:
             return -1
-    g = lambda x, defval='': metadata.get(x, defval)
+    def g(x, defval=''):
+        return metadata.get(x, defval)
     theme = Theme(g('title'), g('author'), safe_int(g('version', -1)), g('description'), g('license', 'Unknown'), g('url', None))
 
     ans = Report(path, name_map, extra, missing, theme)
diff --git a/src/calibre/gui2/lrf_renderer/text.py b/src/calibre/gui2/lrf_renderer/text.py
index fa6356f3ea..6158af6e1c 100644
--- a/src/calibre/gui2/lrf_renderer/text.py
+++ b/src/calibre/gui2/lrf_renderer/text.py
@@ -11,10 +11,14 @@ from calibre.ebooks.lrf.fonts import LIBERATION_FONT_MAP
 from calibre.ebooks.hyphenate import hyphenate_word
 from polyglot.builtins import string_or_bytes
 
-WEIGHT_MAP = lambda wt : int((wt/10)-1)
-NULL       = lambda a, b: a
-COLOR      = lambda a, b: QColor(*a)
-WEIGHT     = lambda a, b: WEIGHT_MAP(a)
+def WEIGHT_MAP(wt):
+    return int(wt / 10 - 1)
+def NULL(a, b):
+    return a
+def COLOR(a, b):
+    return QColor(*a)
+def WEIGHT(a, b):
+    return WEIGHT_MAP(a)
 
 
 class PixmapItem(QGraphicsPixmapItem):
diff --git a/src/calibre/gui2/metadata/diff.py b/src/calibre/gui2/metadata/diff.py
index 73bcd650b5..c59ddeeee4 100644
--- a/src/calibre/gui2/metadata/diff.py
+++ b/src/calibre/gui2/metadata/diff.py
@@ -783,7 +783,8 @@ if __name__ == '__main__':
     ids = sorted(db.all_ids(), reverse=True)
     ids = tuple(zip(ids[0::2], ids[1::2]))
     gm = partial(db.get_metadata, index_is_id=True, get_cover=True, cover_as_data=True)
-    get_metadata = lambda x:list(map(gm, ids[x]))
+    def get_metadata(x):
+        return list(map(gm, ids[x]))
     d = CompareMany(list(range(len(ids))), get_metadata, db.field_metadata, db=db)
     d.exec()
     for changed, mi in itervalues(d.accepted):
diff --git a/src/calibre/gui2/metadata/single_download.py b/src/calibre/gui2/metadata/single_download.py
index 40928ecc0e..4cfad54656 100644
--- a/src/calibre/gui2/metadata/single_download.py
+++ b/src/calibre/gui2/metadata/single_download.py
@@ -181,7 +181,8 @@ class ResultsModel(QAbstractTableModel):  # {{{
         return None
 
     def sort(self, col, order=Qt.SortOrder.AscendingOrder):
-        key = lambda x: x
+        def key(x):
+            return x
         if col == 0:
             key = attrgetter('gui_rank')
         elif col == 1:
@@ -196,7 +197,8 @@ class ResultsModel(QAbstractTableModel):  # {{{
         elif col == 3:
             key = attrgetter('has_cached_cover_url')
         elif key == 4:
-            key = lambda x: bool(x.comments)
+            def key(x):
+                return bool(x.comments)
 
         self.beginResetModel()
         self.results.sort(key=key, reverse=order==Qt.SortOrder.AscendingOrder)
diff --git a/src/calibre/gui2/tag_browser/ui.py b/src/calibre/gui2/tag_browser/ui.py
index 0d52e5a425..bd7f07b26e 100644
--- a/src/calibre/gui2/tag_browser/ui.py
+++ b/src/calibre/gui2/tag_browser/ui.py
@@ -267,7 +267,8 @@ class TagBrowserMixin:  # {{{
 
         db = self.current_db
         if category == 'series':
-            key = lambda x:sort_key(title_sort(x))
+            def key(x):
+                return sort_key(title_sort(x))
         else:
             key = sort_key
 
diff --git a/src/calibre/gui2/tweak_book/diff/highlight.py b/src/calibre/gui2/tweak_book/diff/highlight.py
index ff758a38d5..07c6a757b9 100644
--- a/src/calibre/gui2/tweak_book/diff/highlight.py
+++ b/src/calibre/gui2/tweak_book/diff/highlight.py
@@ -69,7 +69,8 @@ def pygments_lexer(filename):
         from pygments.util import ClassNotFound
     except ImportError:
         return None
-    glff = lambda n: get_lexer_for_filename(n, stripnl=False)
+    def glff(n):
+        return get_lexer_for_filename(n, stripnl=False)
     try:
         return glff(filename)
     except ClassNotFound:
diff --git a/src/calibre/gui2/tweak_book/diff/main.py b/src/calibre/gui2/tweak_book/diff/main.py
index 7257379d95..04e8340fac 100644
--- a/src/calibre/gui2/tweak_book/diff/main.py
+++ b/src/calibre/gui2/tweak_book/diff/main.py
@@ -423,7 +423,8 @@ class Diff(Dialog):
             self.busy.setVisible(True)
             return True
 
-        kwargs = lambda name: {'context':self.context, 'beautify':self.beautify, 'syntax':syntax_map.get(name, None)}
+        def kwargs(name):
+            return {'context': self.context, 'beautify': self.beautify, 'syntax': syntax_map.get(name, None)}
 
         if isinstance(changed_names, dict):
             for name, other_name in sorted(iteritems(changed_names), key=lambda x:numeric_sort_key(x[0])):
diff --git a/src/calibre/gui2/tweak_book/editor/smarts/html.py b/src/calibre/gui2/tweak_book/editor/smarts/html.py
index aee0d952f3..733fc66e95 100644
--- a/src/calibre/gui2/tweak_book/editor/smarts/html.py
+++ b/src/calibre/gui2/tweak_book/editor/smarts/html.py
@@ -85,7 +85,8 @@ def find_closest_containing_tag(block, offset, max_tags=sys.maxsize):
     ''' Find the closest containing tag. To find it, we search for the first
     opening tag that does not have a matching closing tag before the specified
     position. Search through at most max_tags. '''
-    prev_tag_boundary = lambda b, o: next_tag_boundary(b, o, forward=False)
+    def prev_tag_boundary(b, o):
+        return next_tag_boundary(b, o, forward=False)
 
     block, boundary = prev_tag_boundary(block, offset)
     if block is None:
diff --git a/src/calibre/gui2/tweak_book/editor/smarts/python.py b/src/calibre/gui2/tweak_book/editor/smarts/python.py
index 991ad921fa..4a4fcd3770 100644
--- a/src/calibre/gui2/tweak_book/editor/smarts/python.py
+++ b/src/calibre/gui2/tweak_book/editor/smarts/python.py
@@ -13,7 +13,8 @@ from calibre.gui2.tweak_book.editor.smarts.utils import (
     get_text_before_cursor, get_leading_whitespace_on_block as lw,
     smart_home, smart_backspace, smart_tab)
 
-get_leading_whitespace_on_block = lambda editor, previous=False: expand_tabs(lw(editor, previous=previous))
+def get_leading_whitespace_on_block(editor, previous=False):
+    return expand_tabs(lw(editor, previous=previous))
 
 tw = 4  # The tab width (hardcoded to the pep8 value)
 
diff --git a/src/calibre/gui2/tweak_book/editor/smarts/utils.py b/src/calibre/gui2/tweak_book/editor/smarts/utils.py
index ebaa9d9c1e..ff1f2a65f8 100644
--- a/src/calibre/gui2/tweak_book/editor/smarts/utils.py
+++ b/src/calibre/gui2/tweak_book/editor/smarts/utils.py
@@ -16,7 +16,8 @@ def get_text_around_cursor(editor, before=True):
 
 
 get_text_before_cursor = get_text_around_cursor
-get_text_after_cursor = lambda editor: get_text_around_cursor(editor, before=False)
+def get_text_after_cursor(editor):
+    return get_text_around_cursor(editor, before=False)
 
 
 def is_cursor_on_wrapped_line(editor):
diff --git a/src/calibre/gui2/tweak_book/editor/snippets.py b/src/calibre/gui2/tweak_book/editor/snippets.py
index 2f1a474975..80490f3f6c 100644
--- a/src/calibre/gui2/tweak_book/editor/snippets.py
+++ b/src/calibre/gui2/tweak_book/editor/snippets.py
@@ -26,7 +26,8 @@ from calibre.utils.icu import string_length as strlen
 from calibre.utils.localization import localize_user_manual_link
 from polyglot.builtins import codepoint_to_chr, iteritems, itervalues
 
-string_length = lambda x: strlen(str(x))  # Needed on narrow python builds, as subclasses of unicode dont work
+def string_length(x):
+    return strlen(str(x))  # Needed on narrow python builds, as subclasses of unicode dont work
 KEY = Qt.Key.Key_J
 MODIFIER = Qt.KeyboardModifier.MetaModifier if ismacos else Qt.KeyboardModifier.ControlModifier
 
@@ -97,10 +98,12 @@ def escape_funcs():
     if escape is None:
         escapem = {('\\' + x):codepoint_to_chr(i+1) for i, x in enumerate('\\${}')}
         escape_pat = re.compile('|'.join(map(re.escape, escapem)))
-        escape = lambda x: escape_pat.sub(lambda m: escapem[m.group()], x.replace(r'\\', '\x01'))
+        def escape(x):
+            return escape_pat.sub(lambda m: escapem[m.group()], x.replace('\\\\', '\x01'))
         unescapem = {v:k[1] for k, v in iteritems(escapem)}
         unescape_pat = re.compile('|'.join(unescapem))
-        unescape = lambda x:unescape_pat.sub(lambda m:unescapem[m.group()], x)
+        def unescape(x):
+            return unescape_pat.sub(lambda m: unescapem[m.group()], x)
     return escape, unescape
 
 
diff --git a/src/calibre/gui2/tweak_book/editor/syntax/base.py b/src/calibre/gui2/tweak_book/editor/syntax/base.py
index e7f8e87772..72e9aff14f 100644
--- a/src/calibre/gui2/tweak_book/editor/syntax/base.py
+++ b/src/calibre/gui2/tweak_book/editor/syntax/base.py
@@ -64,9 +64,11 @@ class SimpleUserData(QTextBlockUserData):
 
 class SyntaxHighlighter:
 
-    create_formats_func = lambda highlighter: {}
+    def create_formats_func(highlighter):
+        return {}
     spell_attributes = ()
-    tag_ok_for_spell = lambda x: False
+    def tag_ok_for_spell(x):
+        return False
     user_data_factory = SimpleUserData
 
     def __init__(self):
diff --git a/src/calibre/gui2/tweak_book/live_css.py b/src/calibre/gui2/tweak_book/live_css.py
index 576ba52ec3..cefe9c5a76 100644
--- a/src/calibre/gui2/tweak_book/live_css.py
+++ b/src/calibre/gui2/tweak_book/live_css.py
@@ -142,7 +142,8 @@ class Declaration(QWidget):
 
     def do_layout(self):
         fm = self.fontMetrics()
-        bounding_rect = lambda text: fm.boundingRect(0, 0, 10000, 10000, Cell.FLAGS, text)
+        def bounding_rect(text):
+            return fm.boundingRect(0, 0, 10000, 10000, Cell.FLAGS, text)
         line_spacing = 2
         side_margin = Cell.SIDE_MARGIN
         self.rows = []
diff --git a/src/calibre/gui2/tweak_book/widgets.py b/src/calibre/gui2/tweak_book/widgets.py
index 034d34bae2..bc9e2bb889 100644
--- a/src/calibre/gui2/tweak_book/widgets.py
+++ b/src/calibre/gui2/tweak_book/widgets.py
@@ -806,7 +806,8 @@ class InsertSemantics(Dialog):
         return QSize(800, 600)
 
     def create_known_type_map(self):
-        _ = lambda x: x
+        def _(x):
+            return x
         self.epubtype_guide_map = {v: k for k, v in guide_epubtype_map.items()}
         self.known_type_map = {
             'titlepage': _('Title page'),
diff --git a/src/calibre/gui2/viewer/bookmarks.py b/src/calibre/gui2/viewer/bookmarks.py
index 62b5fec5c2..16483bb4ff 100644
--- a/src/calibre/gui2/viewer/bookmarks.py
+++ b/src/calibre/gui2/viewer/bookmarks.py
@@ -172,7 +172,8 @@ class BookmarkManager(QWidget):
     def set_bookmarks(self, bookmarks=()):
         csb = self.current_sort_by
         if csb in ('name', 'title'):
-            sk = lambda x: primary_sort_key(x['title'])
+            def sk(x):
+                return primary_sort_key(x['title'])
         elif csb == 'timestamp':
             sk = itemgetter('timestamp')
         else:
diff --git a/src/calibre/gui2/viewer/search.py b/src/calibre/gui2/viewer/search.py
index 8129a5fc7e..112d381118 100644
--- a/src/calibre/gui2/viewer/search.py
+++ b/src/calibre/gui2/viewer/search.py
@@ -363,9 +363,11 @@ def search_in_name(name, search_query, ctx_size=75):
 
     else:
         spans = []
-        miter = lambda: spans
+        def miter():
+            return spans
         if raw:
-            a = lambda s, l: spans.append((s, s + l))
+            def a(s, l):
+                return spans.append((s, s + l))
             primary_collator_without_punctuation().find_all(search_query.text, raw, a, search_query.mode == 'word')
 
     for (start, end) in miter():
diff --git a/src/calibre/library/caches.py b/src/calibre/library/caches.py
index ebab78c06c..fc4434b799 100644
--- a/src/calibre/library/caches.py
+++ b/src/calibre/library/caches.py
@@ -437,21 +437,26 @@ class ResultCache(SearchQueryParser):  # {{{
 
         if val_func is None:
             loc = self.field_metadata[location]['rec_index']
-            val_func = lambda item, loc=loc: item[loc]
+            def val_func(item, loc=loc):
+                return item[loc]
         q = ''
         cast = adjust = lambda x: x
         dt = self.field_metadata[location]['datatype']
 
         if query == 'false':
             if dt == 'rating' or location == 'cover':
-                relop = lambda x,y: not bool(x)
+                def relop(x, y):
+                    return (not bool(x))
             else:
-                relop = lambda x,y: x is None
+                def relop(x, y):
+                    return (x is None)
         elif query == 'true':
             if dt == 'rating' or location == 'cover':
-                relop = lambda x,y: bool(x)
+                def relop(x, y):
+                    return bool(x)
             else:
-                relop = lambda x,y: x is not None
+                def relop(x, y):
+                    return (x is not None)
         else:
             relop = None
             for k in self.numeric_search_relops.keys():
@@ -462,14 +467,19 @@ class ResultCache(SearchQueryParser):  # {{{
                 (p, relop) = self.numeric_search_relops['=']
 
             if dt == 'int':
-                cast = lambda x: int(x)
+                def cast(x):
+                    return int(x)
             elif dt == 'rating':
-                cast = lambda x: 0 if x is None else int(x)
-                adjust = lambda x: x//2
+                def cast(x):
+                    return (0 if x is None else int(x))
+                def adjust(x):
+                    return (x // 2)
             elif dt in ('float', 'composite'):
-                cast = lambda x : float(x)
+                def cast(x):
+                    return float(x)
             else:  # count operation
-                cast = (lambda x: int(x))
+                def cast(x):
+                    return int(x)
 
             if len(query) > 1:
                 mult = query[-1:].lower()
@@ -720,9 +730,8 @@ class ResultCache(SearchQueryParser):  # {{{
                 if fm['is_multiple'] and \
                         len(query) > 1 and query.startswith('#') and \
                         query[1:1] in '=<>!':
-                    vf = lambda item, loc=fm['rec_index'], \
-                                ms=fm['is_multiple']['cache_to_list']:\
-                                len(item[loc].split(ms)) if item[loc] is not None else 0
+                    def vf(item, loc=fm['rec_index'], ms=fm['is_multiple']['cache_to_list']):
+                        return (len(item[loc].split(ms)) if item[loc] is not None else 0)
                     return self.get_numeric_matches(location, query[1:],
                                                     candidates, val_func=vf)
 
diff --git a/src/calibre/library/catalogs/epub_mobi_builder.py b/src/calibre/library/catalogs/epub_mobi_builder.py
index 6e3da4bbf4..18c706dde9 100644
--- a/src/calibre/library/catalogs/epub_mobi_builder.py
+++ b/src/calibre/library/catalogs/epub_mobi_builder.py
@@ -1261,7 +1261,7 @@ class CatalogBuilder:
         else:
             # Validate custom field is usable as a genre source
             field_md = self.db.metadata_for_field(self.opts.genre_source_field)
-            if field_md is None or not field_md['datatype'] in ['enumeration', 'text']:
+            if field_md is None or field_md['datatype'] not in ['enumeration', 'text']:
                 all_custom_fields = self.db.custom_field_keys()
                 eligible_custom_fields = []
                 for cf in all_custom_fields:
diff --git a/src/calibre/library/database2.py b/src/calibre/library/database2.py
index 61a714cb4a..200f95e584 100644
--- a/src/calibre/library/database2.py
+++ b/src/calibre/library/database2.py
@@ -188,7 +188,8 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         # we need to do it before we call initialize_dynamic
         if apply_default_prefs and default_prefs is not None:
             if progress_callback is None:
-                progress_callback = lambda x, y: True
+                def progress_callback(x, y):
+                    return True
             dbprefs = DBPrefs(self)
             progress_callback(None, len(default_prefs))
             for i, key in enumerate(default_prefs):
@@ -1972,32 +1973,39 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
                     icon_map[category] = icon
 
             datatype = cat['datatype']
-            avgr = lambda x: 0.0 if x.rc == 0 else x.rt/x.rc
+            def avgr(x):
+                return (0.0 if x.rc == 0 else x.rt / x.rc)
             # Duplicate the build of items below to avoid using a lambda func
             # in the main Tag loop. Saves a few %
             if datatype == 'rating':
-                formatter = (lambda x:'\u2605'*int(x//2))
-                avgr = lambda x: x.n
+                def formatter(x):
+                    return ('★' * int(x // 2))
+                def avgr(x):
+                    return x.n
                 # eliminate the zero ratings line as well as count == 0
                 items = [v for v in tcategories[category].values() if v.c > 0 and v.n != 0]
             elif category == 'authors':
                 # Clean up the authors strings to human-readable form
-                formatter = (lambda x: x.replace('|', ','))
+                def formatter(x):
+                    return x.replace('|', ',')
                 items = [v for v in tcategories[category].values() if v.c > 0]
             elif category == 'languages':
                 # Use a human readable language string
                 formatter = calibre_langcode_to_name
                 items = [v for v in tcategories[category].values() if v.c > 0]
             else:
-                formatter = (lambda x:str(x))
+                def formatter(x):
+                    return str(x)
                 items = [v for v in tcategories[category].values() if v.c > 0]
 
             # sort the list
             if sort == 'name':
-                kf = lambda x:sort_key(x.s)
+                def kf(x):
+                    return sort_key(x.s)
                 reverse=False
             elif sort == 'popularity':
-                kf = lambda x: x.c
+                def kf(x):
+                    return x.c
                 reverse=True
             else:
                 kf = avgr
@@ -3597,7 +3605,8 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
 
     def move_library_to(self, newloc, progress=None):
         if progress is None:
-            progress = lambda x:x
+            def progress(x):
+                return x
         if not os.path.exists(newloc):
             os.makedirs(newloc)
         old_dirs = set()
diff --git a/src/calibre/linux.py b/src/calibre/linux.py
index f02c6b9eee..0843c0ea08 100644
--- a/src/calibre/linux.py
+++ b/src/calibre/linux.py
@@ -1136,7 +1136,8 @@ X-GNOME-UsesNotifications=true
 
 
 def get_appdata():
-    _ = lambda x: x  # Make sure the text below is not translated, but is marked for translation
+    def _(x):
+        return x  # Make sure the text below is not translated, but is marked for translation
     return {
         'calibre-gui': {
             'name':'calibre',
diff --git a/src/calibre/spell/import_from.py b/src/calibre/spell/import_from.py
index 72a5a2c63d..90d3fb10fe 100644
--- a/src/calibre/spell/import_from.py
+++ b/src/calibre/spell/import_from.py
@@ -19,7 +19,8 @@ NS_MAP = {
     'manifest': 'http://openoffice.org/2001/manifest',
 }
 
-XPath = lambda x: etree.XPath(x, namespaces=NS_MAP)
+def XPath(x):
+    return etree.XPath(x, namespaces=NS_MAP)
 BUILTIN_LOCALES = {'en-US', 'en-GB', 'es-ES'}
 
 
diff --git a/src/calibre/utils/bibtex.py b/src/calibre/utils/bibtex.py
index 4063bb24b6..7784b07fd4 100644
--- a/src/calibre/utils/bibtex.py
+++ b/src/calibre/utils/bibtex.py
@@ -2167,7 +2167,6 @@ utf8enc2latex_mapping = {  # {{{
     # Items from simple list
     '\u0106': "{\\a\\'C}",
     '\u0408': '{\\CYRJE}',
-    '\u20ac': '{\\texteuro}',
     '\u2191': '{\\textuparrow}',
     '\u0493': '{\\cyrghcrs}',
     '\u2116': '{\\textnumero}',
diff --git a/src/calibre/utils/date.py b/src/calibre/utils/date.py
index b401f03a3e..d9045d2b5f 100644
--- a/src/calibre/utils/date.py
+++ b/src/calibre/utils/date.py
@@ -151,7 +151,8 @@ def dt_factory(time_t, assume_utc=False, as_utc=True):
     return dt.astimezone(_utc_tz if as_utc else _local_tz)
 
 
-safeyear = lambda x: min(max(x, MINYEAR), MAXYEAR)
+def safeyear(x):
+    return min(max(x, MINYEAR), MAXYEAR)
 
 
 def qt_to_dt(qdate_or_qdatetime, as_utc=True):
diff --git a/src/calibre/utils/icu.py b/src/calibre/utils/icu.py
index 7b63d09528..6ee1c4ed8a 100644
--- a/src/calibre/utils/icu.py
+++ b/src/calibre/utils/icu.py
@@ -231,7 +231,8 @@ def capitalize(x):
 try:
     swapcase = _icu.swap_case
 except AttributeError:  # For people running from source
-    swapcase = lambda x:x.swapcase()
+    def swapcase(x):
+        return x.swapcase()
 
 find = make_two_arg_func(collator, 'find')
 primary_find = make_two_arg_func(primary_collator, 'find')
diff --git a/src/calibre/utils/icu_test.py b/src/calibre/utils/icu_test.py
index b0edf01b76..f7d6377c40 100644
--- a/src/calibre/utils/icu_test.py
+++ b/src/calibre/utils/icu_test.py
@@ -120,7 +120,8 @@ class TestICU(unittest.TestCase):
         self.ae((0, 5), icu.primary_no_punc_find('abcd', 'ab cd'))
         # test find all
         m = []
-        a = lambda p,l : m.append((p, l))
+        def a(p, l):
+            return m.append((p, l))
         icu.primary_collator_without_punctuation().find_all('a', 'a a🐱a', a)
         self.ae(m, [(0, 1), (2, 1), (5, 1)])
         # test find whole words
diff --git a/src/calibre/utils/search_query_parser_test.py b/src/calibre/utils/search_query_parser_test.py
index 9f6a00576c..acfd90f2b1 100644
--- a/src/calibre/utils/search_query_parser_test.py
+++ b/src/calibre/utils/search_query_parser_test.py
@@ -334,9 +334,11 @@ class Tester(SearchQueryParser):
         if location in self.fields.keys():
             getter = operator.itemgetter(self.fields[location])
         elif location == 'all':
-            getter = lambda y: ''.join(x if x else '' for x in y)
+            def getter(y):
+                return ''.join(x if x else '' for x in y)
         else:
-            getter = lambda x: ''
+            def getter(x):
+                return ''
 
         if not query:
             return set()
diff --git a/src/calibre/utils/wmf/parse.py b/src/calibre/utils/wmf/parse.py
index 3881dfbdc0..59b23cf53f 100644
--- a/src/calibre/utils/wmf/parse.py
+++ b/src/calibre/utils/wmf/parse.py
@@ -108,7 +108,6 @@ class WMF:
                 247: 'CreatePalette',
                 248: 'CreateBrush',
                 322: 'DibCreatePatternBrush',
-                496: 'DeleteObject',
                 505: 'CreatePatternBrush',
                 762: 'CreatePenIndirect',
                 763: 'CreateFontIndirect',
diff --git a/src/css_selectors/tests.py b/src/css_selectors/tests.py
index c06cc8737e..e07c6cbcfe 100644
--- a/src/css_selectors/tests.py
+++ b/src/css_selectors/tests.py
@@ -745,7 +745,8 @@ by William Shakespeare
     def test_select_shakespeare(self):
         document = html.document_fromstring(self.HTML_SHAKESPEARE)
         select = Select(document)
-        count = lambda s: sum(1 for r in select(s))
+        def count(s):
+            return sum(1 for r in select(s))
 
         # Data borrowed from http://mootools.net/slickspeed/