Roller Coaster (CodeEval) in Python 3.x

main.py

# coding=utf-8
import sys


def main():
    with open(sys.argv[1], "r") as f:
        for line in f:
            upper_flg = True
            for s in line:
                if s.isalpha():
                    if upper_flg:
                        sys.stdout.write(s.upper())
                    else:
                        sys.stdout.write(s.lower())
                    upper_flg = not upper_flg
                else:
                    sys.stdout.write(s)


if __name__ == "__main__":
    main()