public NateDocumentBackedEngine select(String selector) {
   selector = selector.trim();
   if (selector.startsWith(CONTENT_SELECTION_FLAG)) {
     return new NateDocumentBackedEngine(
         document.copyContentOf(selector.substring(CONTENT_SELECTION_FLAG.length())));
   }
   return new NateDocumentBackedEngine(document.copy(selector));
 }
 public NateDocumentBackedEngine inject(Object data) {
   NateDocument newDocument = document.copy();
   NateTransformers.from(data).transform(newDocument);
   return new NateDocumentBackedEngine(newDocument);
 }