Rule Definition
Accessing uninitialized variables is a typical source of errors and unexpected behaviour. Overriding the __init__ method of an ancestor class without initializing it can leave unitialized instance members.

Remediation
Initialize ancestors when overriding __init__ using consistently non-super methods or super() if their ancestors do.

Violation Code Sample

>>> class A:
>>>     def __init__(self):
>>>         self.x = 3
>>>         self.y = 14
>>>
>>> class B(A):
>>>     def __init__(self):
>>>         self.y = 2

Fixed Code Sample

>>> # approach (1)
>>> class B(A):
>>>     def __init__(self):
>>>         super().__init__()        # in Python2: super(B, self).__init__()
>>>         self.y = 2
>>>
>>> # approach (2)
>>> class B(A):
>>>     def __init__(self):
>>>         A.__init__()
>>>         self.y = 2