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              </ul>
            </li>
              </ul>
            </li>
            <li class="nav-item" data-level="2"><a href="#part-4-additive-synthesis" class="nav-link">Part 4: Additive synthesis</a>
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            <li class="nav-item" data-level="3"><a href="#example-1-sine-wave-generator" class="nav-link">Example 1: sine wave generator</a>
              <ul class="nav flex-column">
              </ul>
            </li>
            <li class="nav-it