def set_session_data(self, session_id, key, value):
        sess = self._get_session_info(session_id)
        sess.setdefault('serverdict', {})[key] = value
        self._save_session(sess)
Store a key-value pair into the sessions data associated with this
dataset/ETHPy150Open matrix-org/synapse/synapse/handlers/auth.py/AuthHandler.set_session_data