1. api := router.Group("/api", clevergo.RouteGroupMiddleware(
    2.     // middleware for APIs, such as CORS, authenticator, authorization.
    3.     clevergo.WrapHH(cors.Default().Handler), // https://github.com/rs/cors
    4. ))
    6. apiV1 := api.Group("/v1", clevergo.RouteGroupMiddleware(
    7.     // middleware for v1's APIs
    8. ))
    10. apiV2 := api.Group("/v2", clevergo.RouteGroupMiddleware(
    11.     // middleware for v2's APIs
    12. ))