@Override
	protected void onRestoreInstanceState(Parcelable state) {
		SavedState savedState = (SavedState) state;
		super.onRestoreInstanceState(savedState.getSuperState());
		if (savedState.currentScreen != INVALID_SCREEN) {
			mCurrentPage = savedState.currentScreen;
		}
	}
Snap pager to the specified page.

@param whichPage
           Zero based index of the page.
@param duration
           Duration in milliseconds of scrolling to the chosen page.
app/src/main/java/pro/alexzaitsev/freepager/library/view/core/VerticalPager.java