(backend_type, default, known_backends, help)
return add_argument(
        '--%s_backend' % backend_type,
        default=default,
        type=_load_backend(known_backends, backend_type),
        help=help.format(known_backends=str(known_backends.keys())))
adds the option --<backend_type>_backend with given `default`, where
    the `type=` function loads the chosen backend as a python object

    Only 2 backends are supported:  --configuration_backend and --queue_backend

    `backend_type` - either "configuration" or "queue"
    `known_backends` - Stolos-supported backends for the given `backend_type`
    `default` - the argparse default= option
    `help` - the argparse help= option
adds the option --<backend_type>_backend with given `default`, where
    the `type=` function loads the chosen backend as a python object
adds the option -- <backend_type > _backend with given default where the type = function loads the chosen backend as a python object
def backend(backend_type, default, known_backends, help):
    """
    adds the option --<backend_type>_backend with given `default`, where
    the `type=` function loads the chosen backend as a python object

    Only 2 backends are supported:  --configuration_backend and --queue_backend

    `backend_type` - either "configuration" or "queue"
    `known_backends` - Stolos-supported backends for the given `backend_type`
    `default` - the argparse default= option
    `help` - the argparse help= option

    """
    if backend_type not in ['configuration', 'queue']:
        raise UserWarning(
            "The only recognized types of backends are"
            " 'configuration' and 'queue'")

    return add_argument(
        '--%s_backend' % backend_type,
        default=default,
        type=_load_backend(known_backends, backend_type),
        help=help.format(known_backends=str(known_backends.keys())))
def backend ( backend_type , default , known_backends , help ) : if backend_type not in [ 'configuration' , 'queue' ] : raise UserWarning ( "The only recognized types of backends are" " 'configuration' and 'queue'" ) return add_argument ( '--%s_backend' % backend_type , default = default , type = _load_backend ( known_backends , backend_type ) , help = help . format ( known_backends = str ( known_backends . keys ( ) ) ) )