Join a room.

        Args:
            room_id_or_alias (str): Room ID or an alias.

        Returns:
            Room

        Raises:
            MatrixRequestError

def join_room(self, room_id_or_alias):
        """ Join a room.

        Args:
            room_id_or_alias (str): Room ID or an alias.

        Returns:
            Room

        Raises:
            MatrixRequestError
        """
        response = self.api.join_room(room_id_or_alias)
        room_id = (
            response["room_id"] if "room_id" in response else room_id_or_alias
        )
        return self._mkroom(room_id)