"classic" style or old style classes have no built-in type as a base class:
>>> class OldSpam:      # no base class
...     pass
>>> OldSpam.__bases__
()

>>> class NewSpam(object):           # directly inherit from object
...    pass
>>> NewSpam.__bases__
(<type 'object'>,)
>>> class IntSpam(int):              # indirectly inherit from object...
...    pass
>>> IntSpam.__bases__
(<type 'int'>,)
>>> IntSpam.__bases__[0].__bases__   # ... because int inherits from object
(<type 'object'>,)