s="even"><td class="entry"><a class="el" href="classaudio__driver__local_1_1_optional.html#a7b1d0df736739f38994ed29f54cffdf3">is_valid</a></td><td class="entry"><a class="el" href="classaudio__driver__local_1_1_optional.html">Optional&lt; T &gt;</a></td><td class="entry"><span class="mlabel">protected</span></td></tr>
  <tr><td class="entry"><a class="el" href="classaudio__driver__local_1_1_optional.html#a67b76affb3b5d35fa419ac234144038b">operator bool</a>() const</td><td class="entry"><a class="el" href="c