# Pastebin Rx5HwNWJ
class A:
    def f(self): return 1

def callf():
    a = A()
    # warm up method cache
    for i in range(100):
        x = a.f()
    return x

print("before hack", callf())

import gc
d, = gc.get_referents(A.__dict__) # get the underlying dict from the mappingproxy
d['f'] = lambda self: "evil"

print("after hack", callf())