old-new.py

>>> class Foo:
...     
... 
  File "<stdin>", line 3
    
    ^
IndentationError: expected an indented block
>>> class Foo:
...     def __init__(self):
...             return
... 
>>> class Bar(object):
...     def __init__(self):
...             return
... 
>>> dir(Foo)
['__doc__', '__init__', '__module__']
>>> dir(Bar)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__']
>>> f, b = Foo(), Bar()
>>> dir(f)
['__doc__', '__init__', '__module__']
>>> dir(b)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__']
>>>