r">eps</span><span class="special">(</span><span class="identifier">f</span><span class="special">)</span> <span class="special">&gt;&gt;</span> <span class="identifier">rest</span><span class="special">;</span>
</pre>
<p>
            The <a class="link" href="../basics.html#spirit.qi.reference.basics.lazy_argument">Lazy Argument</a>
            <code class="computeroutput"><span class="identifier">f</span></code> is called to do a semantic
            test (say, checking if a symbol is in the symbol table)