Number of Ones (CodeEval) in Python 3.x

main.py

# coding=utf-8
import sys


def number_of_ones(s):
    return bin(s).count("1")


def main():
    with open(sys.argv[1], "r") as f:
        for line in f:
            print(number_of_ones(int(line.rstrip())))


if __name__ == '__main__':
    main()