Make the prefixed classes utility function available

src/calibre/web/feeds/news.py

@@ -39,6 +39,19 @@ def classes(classes):
         'class': lambda x: x and frozenset(x.split()).intersection(q)})
 
 
+def prefixed_classes(classes):
+    q = frozenset(classes.split(' '))
+
+    def matcher(x):
+        if x:
+            for candidate in frozenset(x.split()):
+                for x in q:
+                    if candidate.startswith(x):
+                        return True
+        return False
+    return {'attrs': {'class': matcher}}
+
+
 class LoginFailed(ValueError):
     pass