btn-danger">Danger</button>
            <div class="btn-group" role="group">
              <button id="btnGroupDrop4" type="button" class="btn btn-danger dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false"></button>
              <div class="dropdown-menu" aria-labelledby="btnGroupDrop4">
                <a class="dropdown-item" href="#">Dropdown link</a>
                <a class="dropdown-item" href="#">Dropdown link</a>
              </div>
            </div>
          </div