an>

<span style="color: #000000">    </span><span style="color: #001080">audioVideo</span><span style="color: #000000">.</span><span style="color: #795E26">addObserver</span><span style="color: #000000">(</span><span style="color: #001080">observer</span><span style="color: #000000">);</span>

<span style="color: #000000">    </span><span style="color: #AF00DB">return</span><span style="color: #000000"> (): </span><span style="color: #267F99">void</span><span style="color: #000000"> </span><span style="col