def __update_session_state(self, session: Session, event: Event) -> None:
    """Updates the session state based on the event."""
    if not event.actions or not event.actions.state_delta:
      return
    for key, value in event.actions.state_delta.items():
      if key.startswith(State.TEMP_PREFIX):
        continue
      session.state.update({key: value})
Updates the session state based on the event.
src/google/adk/sessions/base_session_service.py