code: public XHTMLText appendOpenUnorderedListTag(String style) {
          text.halfOpenElement(UL);
          text.optAttribute(STYLE, style);
          text.rightAngleBracket();
          return this;
      }
docs: Appends a tag that creates an unordered list. The unordered part means that the items
  in the list are not in any particular order.
  
  @param style the style of the unordered list
  
  @return this.