code: @Override
    protected ImmutableList<String> parseElements(String s) {
      ImmutableList.Builder<String> titleCollection = ImmutableList.builder();
      Optional<XmlElement> childOpt = XmlConverter.getChildOpt(s, "query", "imageusage");
      if (childOpt.isPresent()) {
        for (XmlElement element : childOpt.get().getChildren("iu")) {
          titleCollection.add(element.getAttributeValue("title"));
        }
      }
      return titleCollection.build();
    }
docs: picks the article name from a MediaWiki api response.
  
  @param s text for parsing