diff --git a/src/calibre/gui2/metadata/single.py b/src/calibre/gui2/metadata/single.py
index 1593c977ff..908275ebcc 100644
--- a/src/calibre/gui2/metadata/single.py
+++ b/src/calibre/gui2/metadata/single.py
@@ -44,7 +44,7 @@ class MetadataSingleDialogBase(ResizableDialog):
         self.rows_to_refresh = set()
         ResizableDialog.__init__(self, parent)
 
-    def setupUi(self, *args): # {{{
+    def setupUi(self, *args):  # {{{
         self.resize(990, 670)
 
         self.download_shortcut = QShortcut(self)
@@ -102,7 +102,7 @@ class MetadataSingleDialogBase(ResizableDialog):
             self.restoreGeometry(bytes(geom))
     # }}}
 
-    def create_basic_metadata_widgets(self): # {{{
+    def create_basic_metadata_widgets(self):  # {{{
         self.basic_metadata_widgets = []
 
         self.languages = LanguagesEdit(self)
@@ -159,7 +159,7 @@ class MetadataSingleDialogBase(ResizableDialog):
         self.series = SeriesEdit(self)
         self.clear_series_button = QToolButton(self)
         self.clear_series_button.setToolTip(
-               _('Clear series') )
+               _('Clear series'))
         self.clear_series_button.clicked.connect(self.series.clear)
         self.series_index = SeriesIndexEdit(self, self.series)
         self.basic_metadata_widgets.extend([self.series, self.series_index])
@@ -240,7 +240,7 @@ class MetadataSingleDialogBase(ResizableDialog):
 
     # }}}
 
-    def create_custom_metadata_widgets(self): # {{{
+    def create_custom_metadata_widgets(self):  # {{{
         self.custom_metadata_widgets_parent = w = QWidget(self)
         layout = QGridLayout()
         w.setLayout(layout)
@@ -250,7 +250,7 @@ class MetadataSingleDialogBase(ResizableDialog):
         self.__custom_col_layouts = [layout]
     # }}}
 
-    def set_custom_metadata_tab_order(self, before=None, after=None): # {{{
+    def set_custom_metadata_tab_order(self, before=None, after=None):  # {{{
         sto = QWidget.setTabOrder
         if getattr(self, 'custom_metadata_widgets', []):
             ans = self.custom_metadata_widgets
@@ -289,7 +289,7 @@ class MetadataSingleDialogBase(ResizableDialog):
         if callable(self.set_current_callback):
             self.set_current_callback(id_)
         # Commented out as it doesn't play nice with Next, Prev buttons
-        #self.fetch_metadata_button.setFocus(Qt.OtherFocusReason)
+        # self.fetch_metadata_button.setFocus(Qt.OtherFocusReason)
 
     # Miscellaneous interaction methods {{{
     def update_window_title(self, *args):
@@ -332,14 +332,15 @@ class MetadataSingleDialogBase(ResizableDialog):
 
     def cover_from_format(self, *args):
         ext = self.formats_manager.get_selected_format()
-        if ext is None: return
+        if ext is None:
+            return
         if ext == 'pdf':
             return self.get_pdf_cover()
         try:
             mi, ext = self.formats_manager.get_selected_format_metadata(self.db,
                     self.book_id)
         except (IOError, OSError) as err:
-            if getattr(err, 'errno', None) == errno.EACCES: # Permission denied
+            if getattr(err, 'errno', None) == errno.EACCES:  # Permission denied
                 import traceback
                 fname = err.filename if err.filename else 'file'
                 error_dialog(self, _('Permission denied'),
@@ -455,7 +456,6 @@ class MetadataSingleDialogBase(ResizableDialog):
             if d.cover_pixmap is not None:
                 self.cover.current_val = pixmap_to_data(d.cover_pixmap)
 
-
     # }}}
 
     def apply_changes(self):
@@ -471,7 +471,7 @@ class MetadataSingleDialogBase(ResizableDialog):
                 self.books_to_refresh |= getattr(widget, 'books_to_refresh',
                         set([]))
             except (IOError, OSError) as err:
-                if getattr(err, 'errno', None) == errno.EACCES: # Permission denied
+                if getattr(err, 'errno', None) == errno.EACCES:  # Permission denied
                     import traceback
                     fname = getattr(err, 'filename', None)
                     p = 'Locked file: %s\n\n'%fname if fname else ''
@@ -564,7 +564,7 @@ class MetadataSingleDialogBase(ResizableDialog):
             try:
                 signal.disconnect()
             except:
-                pass # Fails if view format was never connected
+                pass  # Fails if view format was never connected
         disconnect(self.view_format)
         for b in ('next_button', 'prev_button'):
             x = getattr(self, b, None)
@@ -587,7 +587,7 @@ class Splitter(QSplitter):
         self.frame_resized.emit(ev)
         return QSplitter.resizeEvent(self, ev)
 
-class MetadataSingleDialog(MetadataSingleDialogBase): # {{{
+class MetadataSingleDialog(MetadataSingleDialogBase):  # {{{
 
     def do_layout(self):
         if len(self.db.custom_column_label_map) == 0:
@@ -716,7 +716,7 @@ class MetadataSingleDialog(MetadataSingleDialogBase): # {{{
 
 # }}}
 
-class DragTrackingWidget(QWidget): # {{{
+class DragTrackingWidget(QWidget):  # {{{
 
     def __init__(self, parent, on_drag_enter):
         QWidget.__init__(self, parent)
@@ -727,7 +727,7 @@ class DragTrackingWidget(QWidget): # {{{
 
 # }}}
 
-class MetadataSingleDialogAlt1(MetadataSingleDialogBase): # {{{
+class MetadataSingleDialogAlt1(MetadataSingleDialogBase):  # {{{
 
     cc_two_column = False
     one_line_comments_toolbar = True
@@ -881,7 +881,7 @@ class MetadataSingleDialogAlt1(MetadataSingleDialogBase): # {{{
 
 # }}}
 
-class MetadataSingleDialogAlt2(MetadataSingleDialogBase): # {{{
+class MetadataSingleDialogAlt2(MetadataSingleDialogBase):  # {{{
 
     cc_two_column = False
     one_line_comments_toolbar = True