anchor.diff:    fileRename.click(() => {
       const initialFilename = cd.currentFilename();
       const okInitiallyDisabled = true;
  -    const okClicked = (filename) => {
  +    const okClicked = filename => {
         cd.renameFile(initialFilename, filename);
         cd.loadFile(filename);
       };
  
positive.code:   // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  
    fileNew.click(() => {
      const initialFilename = 'filename' + cd.extensionFilenames()[0];
      const okInitiallyDisabled = !isValidFilename(initialFilename);
      const okClicked = (filename) => {
        cd.newFile(filename, '');
        cd.loadFile(filename);
      };
  
negative.code:   fileDelete.click(() => {
      const initialFilename = cd.currentFilename();
      const okInitiallyDisabled = false;
      const okClicked = filename => {
        cd.deleteFile(filename);
        cd.loadFile('stdout');
      };
  