code: def attributes(self) -> Sequence[bytes]:
          
          ret: List[bytes] = []
          if not self.exists:
              ret.append(b'Noselect')
          if self.has_children:
              ret.append(b'HasChildren')
          else:
              ret.append(b'HasNoChildren')
          if self.marked is True:
              ret.append(b'Marked')
          elif self.marked is False:
              ret.append(b'Unmarked')
          return ret
docs: The mailbox attributes that should be returned with the mailbox
          in a ``LIST`` response, e.g. ``\\Noselect``.
  
          See Also:
              `RFC 3348 <https://tools.ietf.org/html/rfc3348>`_