How to navigate from Content Page to Shell in native forms?

In my xamarin forms native 3.x project, currently I am navigating from content page to content page using below code

Android.Support.V4.App.Fragment mainPage = new ContentPage().CreateSupportFragment(this);

    SupportFragmentManager
        .BeginTransaction()
        .Replace(Resource.Id.fragment_frame_layout, mainPage)
        .Commit();

But this is not working in case of navigation from content page to Shell (Xamarin Forms 4.0.0).

Any help is appreciated.