anchor.diff:            output.val(status + ': is the cyber-dojo server down?');
           }
         },
  -      complete: (xhr, status) => {
  +      complete: (_xhr, _status) => {
           testSpinner.hide();
           testOverlay.remove();
           testButton.enable();
  
positive.code:     // 3. when you revert
  
      cd.saveCodeFromSyntaxHighlightEditors();
  
      const form = testButton.closest('form');
      cd.storeOutgoingFileHashes();
      $.ajax({
        timeout: 30000, // 30 seconds (twice server timeout)
           type: 'POST',
            url: form.attr('action'),
           data: form.serialize(),
  
        beforeSend: (xhr, settings) => {
          testButton.disable();
          testOverlay.insertAfter($('body'));
          testSpinner.show();
        },
        success: (data, status, xhr) => {
          cd.rebuildFilenameList();
          cd.storeIncomingFileHashes();
        },
        error: (xhr, status, thrown) => {
          const output = cd.fileContentFor('output');
          if (status == 'timeout') {
            output.val(status + ': have you lost your network connection?');
  
negative.code:   const testButton  = $('#test-button');
    const testSpinner = $('#test-spinner');
    const testOverlay = $('<div id="test-overlay"></div>');
  
    const form = testButton.closest('form');
  
    testButton.enable = () => {
      testButton.attr('disabled', false);
  