code: def Forget(self, obj):
          '''Forget we've seen this object.
          '''
          obj = _get_idstr(obj)
          try:
              self.memo.remove(obj)
          except ValueError:
              pasf Forget(self, obj):
          '''Forget we've seen this object.
          '''
          obj = _get_idstr(obj)
          try:
              self.memo.remove(obj)
          except ValueError:
              pass
docs: Forget we've seen this object.