ect.
 All arguments optional.


    <h3>Parameters:</h3>
    <ul>
        <li><span class="parameter">attack</span>
         Attack value.
        </li>
        <li><span class="parameter">release</span>
         Release value.
        </li>
        <li><span class="parameter">level</span>
         Level value, accepts y_min to y_max.
        </li>
        <li><span class="parameter">curve</span>
         Curve of envelope, accepts "lin", "exp" or a number where 0 is linear and positive and negative numbers