docs: def fetch_request_ids(item_ids, cls, attr_name, verification_list=None):
      """Return a list of cls instances for all the ids provided in item_ids.
  
      :param item_ids: The list of ids to fetch objects for
      :param cls: The class to fetch the ids from
      :param attr_name: The name of the attribute for exception purposes
      :param verification_list: If provided, a list of acceptable instances
  
      Raise InvalidId exception using attr_name if any do not
          exist, or are not present in the verification_list.
  
      """
      if not item_ids:
          return []
      items = []
      for item_id in item_ids:
          item = cls.fetch_by_id(item_id)
          if not item or (verification_list is not None and
                          item not in verification_list):
              raise InvalidId(attr_name)
          items.append(item)
      return items