code: def _enum_from_direction(direction):
      
      if isinstance(direction, int):
          return direction
  
      if direction == Query.ASCENDING:
          return enums.StructuredQuery.Direction.ASCENDING
      elif direction == Query.DESCENDING:
          return enums.StructuredQuery.Direction.DESCENDING
      else:
          msg = _BAD_DIR_STRING.format(direction, Query.ASCENDING, Query.DESCENDING)
          raise ValueError(msg)
docs: Convert a string representation of a direction to an enum.
  
      Args:
          direction (str): A direction to order by. Must be one of
              :attr:`~.firestore.Query.ASCENDING` or
              :attr:`~.firestore.Query.DESCENDING`.
  
      Returns:
          int: The enum corresponding to ``direction``.
  
      Raises:
          ValueError: If ``direction`` is not a valid direction.