code: def expunge(self, instance):
          '''Remove *instance* from the :class:`Session`. Instance could be a
  :class:`Model` or an id.
  
  :parameter instance: a :class:`Model` or an *id*
  :rtype: the :class:`Model` removed from session or ``None`` if
      it was not in the session.
  '''
          instance = self.pop(instance)
          instance.session = None
          return instancf expunge(self, instance):
          '''Remove *instance* from the :class:`Session`. Instance could be a
  :class:`Model` or an id.
  
  :parameter instance: a :class:`Model` or an *id*
  :rtype: the :class:`Model` removed from session or ``None`` if
      it was not in the session.
  '''
          instance = self.pop(instance)
          instance.session = None
          return instance
docs: Remove *instance* from the :class:`Session`. Instance could be a
  :class:`Model` or an id.
  
  :parameter instance: a :class:`Model` or an *id*
  :rtype: the :class:`Model` removed from session or ``None`` if
      it was not in the session.