class SpecialThing(Thing):

  def save(self, *args, **kwargs):
      # If only I could `my_kwarg = kwargs.delete('my_kwarg')
      my_kwarg = 'my_kwarg' in kwargs
      if my_kwarg:
          kwargs.pop('my_kwarg')
      result = super(SpecialThing, self).save(*args, **kwargs)
      if my_kwarg:
          self.do_more_stuff()
      return result