docs: def create_session(self, options):
          """Create the session factory used by :meth:`create_scoped_session`.
  
          The factory **must** return an object that SQLAlchemy recognizes as a session,
          or registering session events may raise an exception.
  
          Valid factories include a :class:`~sqlalchemy.orm.session.Session`
          class or a :class:`~sqlalchemy.orm.session.sessionmaker`.
  
          The default implementation creates a ``sessionmaker`` for :class:`SignallingSession`.
  
          :param options: dict of keyword arguments passed to session class
          """
  
          return orm.sessionmaker(class_=SignallingSession, db=self, **options)