I've copy & pasted the example from the documentation and added the following lines to it (attached full file)

args = parser.parse_args('')
args.func(args)

Following the style / way show in the documentation, I'd expect this block to work (3.2.2 behaviour). I do however understand from a logical point that this does not work:

* no subparsers are required
* no argument is required

=> args.func is never setup

One could check for this situation using getattr:

    try:
        a = getattr(args, "func")
    except AttributeError:
        parser['main'].print_help()
        sys.exit(0)

Though this look quite manual compared to the usual way of using argparse.