code: function () {
        var val = '"' + this.value + '"';
        if (this.lang !== undefined) {
          val += '@' + this.lang;
        } else if (this.datatype !== undefined) {
          val += '^^<' + this.datatype + '>';
        }
        return val;
      }
docs: Returns a string representing this resource in <a href="http://www.w3.org/TeamSubmission/turtle/#literal">Turtle format</a>.
  @returns {String}