How to start the Google home screen on Android when it's not the default?

I have a home screen repla开发者_开发问答cement app. It is set via the GUI to always be used as the home screen. How can I get that activity to start the original home screen on demand? Is there a published activity name for it? I want my replacement home screen to remain the default.

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The name of activity is

com.android.launcher.Launcher