protected PaperOnboardingPage toggleToNextElement(){
  if (mActiveElementIndex + 1 < mElements.size()) {
    mActiveElementIndex++;
    return mElements.size() > mActiveElementIndex ? mElements.get(mActiveElementIndex) : null;
  }
 else   return null;
}

protected PaperOnboardingPage toggleToNextElement ( ) { if ( mActiveElementIndex + 1 < mElements . size ( ) ) { mActiveElementIndex ++ ; return mElements . size ( ) > mActiveElementIndex ? mElements . get ( mActiveElementIndex ) : null ; } else return null ; }
changes active element to the next one and returns a new content
