"identifier">of</span> <span class="keyword">true</span><span class="special">,</span> <span class="identifier">otherwise</span> <span class="keyword">false</span><span class="special">.</span>

<span class="identifier">A</span> <span class="identifier">popular</span> <span class="identifier">use</span> <span class="identifier">of</span> <span class="identifier">the</span> <span class="identifier">optional</span> <span class="identifier">MPL</span> <span class="identifier">lambda</span> <span class="identif