create custom core service in angular

The document of angularjs shows how to create a service of your own module like this

angular.module("mymodule", []).service("myService", service);

my question is how can I create service like core service like $http ? I try the following, it does not work?

angular.module("ng").service("$http2", service);

Thanks

Your module spelling is wrong, other than that it is working fine

angular.module("ng").service("$http2", service);

Demo: Fiddle