code: function (subTplName, callback) {
              var tpl = S.require(subTplName);
              if (tpl) {
                  callback(undefined, tpl);
              } else {
                  var warning = 'template "' + subTplName + '" does not exist, ' + 'better required or used first for performance!';
                  S.log(warning, 'error');
                  callback(warning, undefined);
              }
          }
docs: get
  @cfg {Function} loader
  @member KISSY.XTemplate.Runtime