docs: def init_app(self, app, sessionstore=None, register_blueprint=True):
          """Flask application initialization.
  
          :param app: The Flask application.
          :param sessionstore: store for sessions. Passed to
              ``flask-kvsession``. If ``None`` then Redis is configured.
              (Default: ``None``)
          :param register_blueprint: If ``True``, the application registers the
              blueprints. (Default: ``True``)
          """
          self.make_session_permanent(app)
          return super(InvenioAccountsUI, self).init_app(
              app, sessionstore=sessionstore,
              register_blueprint=register_blueprint
          )