docs: def ListChildren(self, urn, limit=None, age=NEWEST_TIME):
      """Lists bunch of directories efficiently.
  
      Args:
        urn: Urn to list children.
        limit: Max number of children to list.
        age: The age of the items to retrieve. Should be one of ALL_TIMES,
          NEWEST_TIME or a range.
  
      Returns:
        RDFURNs instances of each child.
      """
      _, children_urns = list(
          self.MultiListChildren([urn], limit=limit, age=age))[0]
      return children_urns