will do, i'm thinking about something like the following just above the `__init__()` method. let me know if it makes sense or needs tweaked.

    # presumably when you have a sub-parser, you want it to provide completion
    # as well. in order to do so, you must include the 'parser_class' parameter
    # to SelfCompletingArgumentParser().add_subparsers().add_parser(). the
    # arguments to that method are passed through to the __init__ method below,
    # which must filter them out before calling super().__init__()