      <li><span class="parameter">y_min</span>
         Minimum value for y axis, defaults to 0.
        </li>
        <li><span class="parameter">y_max</span>
         Maximum value for y axis, defaults to 1.
        </li>
        <li><span class="parameter">attack</span>
         Attack value, defaults to 0.05.
        </li>
        <li><span class="parameter">release</span>
         Release value, defaults to 0.3.
        </li>
        <li><span class="parameter">level</span>
         Level value, accept