code: function (tplContent, name, isModule) {
              var func = compiler.compile(tplContent, name, isModule);
              return substitute(FUNC, {
                  params: func.params.join(','),
                  body: func.source
              });
          }
docs: get template function string
  @param {String} tplContent
  @param {String} [name] xtemplate name
  @param {Boolean} [isModule] whether generated function is used in module
  @return {String}