code: function tryRenameExternalModule(moduleName) {
                  if (renamedDependencies && moduleName.text in renamedDependencies) {
                      return "\"" + renamedDependencies[moduleName.text] + "\"";
                  }
                  return undefined;
              }
docs: /*
  Some bundlers (SystemJS builder) sometimes want to rename dependencies.
  Here we check if alternative name was provided for a given moduleName and return it if possible.