python inheritance remove an attribute

1Think carefully about why you want to do this; you probably don't. Consider not making B inherit from A.
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3The idea of subclassing is to specialise an object. In particular, children of a class should be valid instances of the parent class:
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5>>> class foo(dict): pass
6>>> isinstance(foo(), dict)
7... True
8If you implement this behaviour (with e.g. x = property(lambda: AttributeError)), you are breaking the subclassing concept, and this is Bad.