[jmholla]

`argparse` does it by default:

    >>> import argparse
    >>> p = argparse.ArgumentParser()
    >>> p.add_argument("--foo", "-f", action="store_true")
    >>> p.add_argument("--bar", "-b")
    >>> p.parse_args(["-fb", "baz"])
    Namespace(foo=True, bar='baz')