def exec_args(f):
    """decorator for adding block/targets args for execution
    
    applied to %pxconfig and %%px
    """
    args = [
        magic_arguments.argument('-b', '--block', action="store_const",
            const=True, dest='block',
            help="use blocking (sync) execution",
        ),
        magic_arguments.argument('-a', '--noblock', action="store_const",
            const=False, dest='block',
            help="use non-blocking (async) execution",
        ),
        magic_arguments.argument('-t', '--targets', type=str,
            help="specify the targets on which to execute",
        ),
        magic_arguments.argument('--verbose', action="store_const",
            const=True, dest="set_verbose",
            help="print a message at each execution",
        ),
        magic_arguments.argument('--no-verbose', action="store_const",
            const=False, dest="set_verbose",
            help="don't print any messages",
        ),
    ]
    for a in args:
        f = a(f)
    return f