import types
class A():
    def __init__(self):
        self.a = 0

    def print(self, v):
        print(self.a + v)

    def override_print(self, fn):
        self.print = types.MethodType(fn, self)


def new_print(self, value):
    print(self.a + value * 2)


a = A()
a.override_print(new_print)
a.print(10)