def wraps(fn):
    if (router_class in _supported_routers):
        raise ValueError('Another function is already registered for the router {}'.format(router_class))
    _supported_routers[router_class] = fn
    return fn
def wraps(fn):
    if (router_class in _supported_routers):
        raise ValueError('Another function is already registered for the router {}'.format(router_class))
    _supported_routers[router_class] = fn
    return fn