==== CODE SECTION = WHERE THE CODE APPEARS ==================== -->
          <div class="col-lg-7 text-center .align-middle">
            <div class="v4-v6-toggle">
              <button
                id="button-show-v4"
                onclick="showCodeVersion('v4')"
                type="button"
                class="btn btn-secondary btn-sm active"
              >
                d3 v4
              </button>
              <span> | </span>
              <button
                id="button-show-v6"
   