class lolmyclass:
    def __init__(self):
        self.something = None

class heya:
    def __init__(self):
        self.lol = 5

    def set_some(self, an_obj):
        setattr(an_obj, 'somefunc', self.some_func)

    def some_func(self):
        print(self.lol)

mylol = lolmyclass()
myheya = heya()
myheya.set_some(mylol)
mylol.somefunc()