SequenceField for abstract classes now have a proper name

mongoengine/base/document.py

@@ -672,7 +672,7 @@ class BaseDocument(object):
 
     @classmethod
     def _get_collection_name(cls):
-        """Returns the collection name for this class.
+        """Returns the collection name for this class. None for abstract class
         """
         return cls._meta.get('collection', None)
 

mongoengine/base/metaclasses.py

@@ -424,7 +424,6 @@ class TopLevelDocumentMetaclass(DocumentMetaclass):
         return id_name, id_db_name
 
 
-
 class MetaDict(dict):
 
     """Custom dictionary for meta classes.