        </ul>
            </li>
            <li class="nav-item" data-level="3"><a href="#example-2-delay-of-01-second-on-the-right-channel" class="nav-link">Example 2: Delay of 0.1 second on the right channel</a>
              <ul class="nav flex-column">
              </ul>
            </li>
            <li class="nav-item" data-level="3"><a href="#example-3-the-bouncing-of-sound-on-a-wall" class="nav-link">Example 3: the bouncing of sound on a wall</a>
              <ul class="nav flex-column">
         