#!/usr/bin/env python

import argparse

parser = argparse.ArgumentParser(prog='PROG')
parser.add_argument('--foo')
parser.add_argument('command')
parser.add_argument('args', nargs=argparse.REMAINDER)

try:
    # this works and parses correctly, from the example
    print(parser.parse_args('--foo B cmd --arg1 XX ZZ'.split()))
except SystemExit as e:
    print(e)

try:
    # this works and parses correctly too
    print(parser.parse_args('cmd --arg1 XX ZZ'.split()))
except SystemExit as e:
    print(e)

try:
    # this doesn't work
    print(parser.parse_args('--foo B --arg1 XX ZZ'.split()))
except SystemExit as e:
    print(e)
    
try:
    # this doesn't work
    print(parser.parse_args('--arg1 XX ZZ'.split()))
except SystemExit as e:
    print(e)