-record(user_creation_service, {
    create_user :: fun((binary()) -> gauth@user:user(any())),
    middleware :: list(fun((binary()) -> {ok, binary()} |
        {error, gauth@user@creation:user_creation_error()})),
    finalware :: list(fun((gauth@user:user(any())) -> gauth@user:user(any()))),
    errorware :: list(fun((gauth@user@creation:user_creation_error()) -> gauth@user@creation:user_creation_error()))
}).