SSERT</span><span class="special">(</span><span class="identifier">r</span> <span class="special">&amp;&amp;</span> <span class="identifier">first</span> <span class="special">==</span> <span class="identifier">str</span><span class="special">.</span><span class="identifier">end</span><span class="special">());</span>
<span class="special">}</span>
</pre>
<p>
        </p>
<p>
          The last example shows that the <code class="computeroutput"><span class="identifier">distinct</span><span class="special">