code: function pop(doc) {
      if (doc instanceof Document) {
          _.defer(() => navigationDocument.popToDocument(doc));
      } else {
          _.defer(() => navigationDocument.popDocument());
      }
  }
docs: Pops the recent document or pops all document before the provided document.
  
  @inner
  @alias module:navigation.pop
  
  @param  {Document} [doc]     The document until which we need to pop.