code: def update(self, user, **kwargs):
          
          yield self.get_parent()
  
          if not self.parent.editable:
              err = 'Cannot update child of {} resource'.format(self.parent.state.name)
              raise exceptions.Unauthorized(err)
  
          yield super(SubResource, self).update(user, **kwargs)
docs: If parent resource is not an editable state, should not be able to update