docs: def get_collection_for_cls_name(self, cls_name):
          """
          Returns the collection name for a given document class.
  
          :param cls: The document class for which to return the collection name.
  
          :returns: The collection name for the given class.
          """
          for cls in self.classes:
              if cls.__name__ == cls_name:
                  return self.classes[cls]['collection']
          raise AttributeError("Unknown class name: %s" % cls_name)