        </h6>
<p>
            Semantic predicates allow you to attach a conditional function anywhere
            in the grammar. In this role, the epsilon takes a <a class="link" href="../basics.html#spirit.qi.reference.basics.lazy_argument">Lazy
            Argument</a> that returns <code class="computeroutput"><span class="keyword">true</span></code>
            or <code class="computeroutput"><span class="keyword">false</span></code>. The <a class="link" href="../basics.html#spirit.qi.reference.basics.l