code: def add(self, value, session=None, **kwargs):
          '''Add ``value``, an instance of :attr:`formodel` to the
  :attr:`through` model. This method can only be accessed by an instance of the
  model for which this related manager is an attribute.'''
          s, instance = self.session_instance('add', value, session, **kwargs)
          return s.add(instancef add(self, value, session=None, **kwargs):
          '''Add ``value``, an instance of :attr:`formodel` to the
  :attr:`through` model. This method can only be accessed by an instance of the
  model for which this related manager is an attribute.'''
          s, instance = self.session_instance('add', value, session, **kwargs)
          return s.add(instance)
docs: Add ``value``, an instance of :attr:`formodel` to the
  :attr:`through` model. This method can only be accessed by an instance of the
  model for which this related manager is an attribute.