prog.py

import argparse

parser = argparse.ArgumentParser(description = 'Process some integers.')
parser.add_argument('integers', metavar='N', type=int, nargs='+',
		help = 'an integer for the accumulator')
parser.add_argument('--sum', dest='accumulate', action='store_const',
		const=sum, default=max,
		help = 'sum the integers (default: find the max)')

args = parser.parse_args()
print args.accumulate(args.integers)