How to write a simple callback function?

Question

Python 2.7.10

I wrote the following code to test a simple callback function.

def callback(a, b):
    print(\'Sum = {0}\'.format(a+b))

def main(         


        

Answer 1

Here's what you wanted to do :

def callback(a, b):
    print('Sum = {0}'.format(a+b))

def main(a,b,f=None):
    print('Add any two digits.')
    if f != None:
        f(a,b)

main(1, 2, callback)