Simple ASCII converter CLI in Python

ascii.py

#!/usr/bin/python
import sys

def main():
    if len(sys.argv[1:]) < 2:
        usage()
    elif sys.argv[1] == '-d' or sys.argv[1] == '--decode':
        decode(sys.argv[2:])
    elif sys.argv[1] == '-e' or sys.argv[1] == '--encode':
        encode(" ".join(sys.argv[2:]))
    else:
        usage()
    sys.exit(0)

def decode(nums):
    try:
        print "".join([chr(int(n)) for n in nums])
    except:
        usage()

def encode(string):
    try:
        print " ".join([str(ord(c)) for c in string])
    except:
        usage()

def usage():
    print "Usage:"
    print "./ascii [operation] [data]"
    print "Operations:"
    print "-e --encode    Encodes ASCII characters to their int representation"
    print "-d --decode    Decodes ASCII characters from their int representation"
    print "Examples:"
    print "./ascii -e ABCDEFG"
    print "./ascii -d 65 66 67 68 69 70 71"

if __name__ == '__main__':
    main()