code: def objref(obj):
      
      ref = _objrefs.get(obj)
      if ref is None:
          clsname = obj.__class__.__name__.split('.')[-1]
          seqno = _lastids.setdefault(clsname, 1)
          ref = '{}-{}'.format(clsname, seqno)
          _objrefs[obj] = ref
          _lastids[clsname] += 1
      return ref
docs: Return a string that uniquely and compactly identifies an object.