code: function setupGui() {
    // Create training buttons and info texts
    for (let i = 0; i < NUM_CLASSES; i++) {
      const div = document.createElement('div');
      document.body.appendChild(div);
      div.style.marginBottom = '10px';
  
      // Create training button
      const button = document.createElement('button');
      button.innerText = 'Train ' + i;
      div.appendChild(button);
  
      // Listen for mouse events when clicking the button
      button.addEventListener('click', () => {
        training = i;
        requestAnimationFrame(() => training = -1);
      });
  
      // Create info text
      const infoText = document.createElement('span');
      infoText.innerText = ' No examples added';
      div.appendChild(infoText);
      infoTexts.push(infoText);
    }
  }
docs: Setup training GUI. Adds a training button for each class,
  and sets up mouse events.