async def create_session(
      self,
      *,
      app_name: str,
      user_id: str,
      state: Optional[dict[str, Any]] = None,
      session_id: Optional[str] = None,
  ) -> Session:
    """Creates a new session.

    Args:
      app_name: the name of the app.
      user_id: the id of the user.
      state: the initial state of the session.
      session_id: the client-provided id of the session. If not provided, a
        generated ID will be used.

    Returns:
      session: The newly created session instance.
    """
Creates a new session.

    Args:
      app_name: the name of the app.
      user_id: the id of the user.
      state: the initial state of the session.
      session_id: the client-provided id of the session. If not provided, a
        generated ID will be used.

    Returns:
      session: The newly created session instance.
    
src/google/adk/sessions/base_session_service.py