sum

gistfile1.txt

#!/usr/bin/env python


class A(object):
    def __init__(self, obj):
        self.obj = obj

    def __repr__(self):
        return str(self.obj)

    def __add__(self, other):
        return A(self.obj + other.obj)

    def __radd__(self, other):
        return A(self.obj + other)


if __name__ == '__main__':
    print(A(1) + A(2))
    print(sum([A(1), A(2), A(3)]))