code: def delete(self, instance, session):
          '''delete an *instance*'''
          if instance._meta.type == 'structure':
              return self._delete_structure(instance)
          inst = self.pop(instance)
          instance = inst if inst is not None else instance
          if instance is not None:
              state = instance.get_state()
              if state.persistent:
                  state.deleted = True
                  self._deleted[state.iid] = instance
                  instance.session = session
              else:
                  instance.session = None
              return instancf delete(self, instance, session):
          '''delete an *instance*'''
          if instance._meta.type == 'structure':
              return self._delete_structure(instance)
          inst = self.pop(instance)
          instance = inst if inst is not None else instance
          if instance is not None:
              state = instance.get_state()
              if state.persistent:
                  state.deleted = True
                  self._deleted[state.iid] = instance
                  instance.session = session
              else:
                  instance.session = None
              return instance
docs: delete an *instance*