Add arguments to the command parser.

        Uses argparse syntax.  See documentation at
        https://docs.python.org/3/library/argparse.html.

def add_arguments(self, parser):
        """
        Add arguments to the command parser.

        Uses argparse syntax.  See documentation at
        https://docs.python.org/3/library/argparse.html.
        """
        parser.add_argument(
            '--dry-run',
            action='store_true',
            default=False,
            help="Output what we're going to do, but don't actually do it."
        )
        parser.add_argument(
            '--task-name', '-t',
            default=None,
            help=u"Restrict cleanup to tasks matching the named task.",
        )
        parser.add_argument(
            '--age', '-a',
            type=int,
            default=30,
            help=u"Only delete tasks that have been resolved for at least the specified number of days (default: 30)",
        )