code: public Integer setElement(String title, String image_url, String subtitle)
      {
          HashMap<String, Object> element = new HashMap<String, Object>();
  
          element.put("title", title);
          element.put("image_url", image_url);
          element.put("subtitle", subtitle);
          this.elements.add(element);
  
          return this.elements.size() - 1;
      }
docs: Set Element
  
  @param  title the element title
  @param  image_url the element image url
  @param  subtitle the element subtitle
  @return Integer the element index