code: def is_session_storage_enabled(self, subject=None):
          
          if subject.get_session(False):
              # then use what already exists
              return True
  
          if not self.session_storage_enabled:
              # honor global setting:
              return False
  
          # non-web subject instances can't be saved to web-only session managers:
          if (not hasattr(subject, 'web_registry') and self.session_manager and
                  not isinstance(self.session_manager, session_abcs.NativeSessionManager)):
              return False
  
          return subject.web_registry.session_creation_enabled
docs: Returns ``True`` if session storage is generally available (as determined
          by the super class's global configuration property is_session_storage_enabled
          and no request-specific override has turned off session storage, False
          otherwise.
  
          This means session storage is disabled if the is_session_storage_enabled
          property is False or if a request attribute is discovered that turns off
          session storage for the current request.
  
          :param subject: the ``Subject`` for which session state persistence may
                          be enabled
  
          :returns: ``True`` if session storage is generally available (as
                    determined by the super class's global configuration property
                    is_session_storage_enabled and no request-specific override has
                    turned off session storage, False otherwise.