code: int getItemViewType(T content) {
      Class prototypeClass = getPrototypeClass(content);
      validatePrototypeClass(prototypeClass);
      return getItemViewType(prototypeClass);
    }
docs: Return the item view type used by the adapter to implement recycle mechanism.
  
  @param content to be rendered.
  @return an integer that represents the renderer inside the adapter.