Answering for this question https://twitter.com/nyaocat/status/481791765498720256

nyaocat.py

_some_global_value = 'hoge'

class A(object):
    def __del__(self):
        global _some_global_value
        _some_global_value = 'fuga'

class B(object):
    def hoge(self):
        return _some_global_value


assert B().hoge() == 'hoge'

a = A()
a = B()
assert a.hoge() == 'fuga'