code: function (pkg) {
              var b = pkg[KIRIN_IN_PACKAGE_JSON];
              if (b) {
                  if (typeof b === 'string') {
                      pkg.main = b;
                  }
                  else if (typeof b === 'object' && b.main) {
                      pkg.main = b.main;
                  }
              }
              return pkg;
          }
docs: extensions : this.extensions,