code: public HelpersBuilder addChoose() {
          builder.put(CHOOSE, new ChooseHelper());
          builder.put(WHEN, new ChooseHelper.WhenHelper());
          builder.put(OTHERWISE, new ChooseHelper.OtherwiseHelper());
          return this;
      }
docs: Add an instance of {@link ChooseHelper} with the {@value #CHOOSE} name.
  Also adds the dependent helpers.
  
  @return self