code: @SuppressWarnings("unchecked")
      private <T extends DomElement> List<T> allByTagName(String tagName) {
          return (List<T>) htmlPage.getElementsByTagName(tagName);
      }
docs: Returns all elements of the given HTML tag name as subtypes of {@link DomElement}.
  
  @param tagName HTML tag name
  @param <T>     type of elements
  @return list of DOM elements