tifier">shared</span> <span class="special">{};</span>
<span class="special">};</span>
</pre>
<p>
        It is possible to derive the struct <code class="computeroutput"><span class="identifier">unique</span></code>
        from the type <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">detail</span><span class="special">::</span><span class="identifier">default_check