  draw arc.


    <h3>Parameters:</h3>
    <ul>
        <li><span class="parameter">x</span>
            <span class="types"><span class="type">number</span></span>
         circle center x
        </li>
        <li><span class="parameter">y</span>
            <span class="types"><span class="type">number</span></span>
         circle center y
        </li>
        <li><span class="parameter">r</span>
            <span class="types"><span class="type">number</span></span>
         radius
        </li>
     