code: def _coerce_client_id(client_id):
      
      if isinstance(client_id, type(u'')):
          client_id = client_id.encode('utf-8')
      if not isinstance(client_id, bytes):
          raise TypeError('{!r} is not a valid consumer group (must be'
                          ' str or bytes)'.format(client_id))
      return client_id
docs: Ensure the provided client ID is a byte string. If a text string is
      provided, it is encoded as UTF-8 bytes.
  
      :param client_id: :class:`bytes` or :class:`str` instance