def _unlink(subs, shared):
    """Configure the `doorstop unlink` subparser."""
    info = 'remove a link between two items'
    sub = subs.add_parser('unlink', description=info.capitalize() + '.',
        help=info, **shared)
    sub.add_argument('child', help='child item UID to unlink from parent')
    sub.add_argument('parent', help='parent item UID child is linked to')
