code: @SuppressWarnings({"UnusedReturnValue", "WeakerAccess"})
      public PagerFragment addFragment(String title, Fragment fragment) {
          this.mFragmentTitles.add(title);
          this.mFragments.add(fragment);
  
          return this;
      }
docs: Add a Fragment to this PagerFragment.
  
  @param title    The title of the {@link android.app.Fragment} to be added
  @param fragment The {@link android.app.Fragment} to be added
  @return The current PagerFragmentInstance