python callback function

class Test(object):
    def __init__(self,a):
        self.a = a
 
    def func1(self):   #Call the callback function 
        return self.func2(self.a,self.calls)

    def func2(self,aa,func): #Execute the callback function 
        return func(aa)


    def calls(self,ss):    #callback function
        self.ss = ss+8
        return self.ss


test = Test(8)
print(test.func1())