xpression has <code class="computeroutput"><span class="char">','</span></code> instead of <code class="computeroutput"><span class="identifier">lit</span><span class="special">(</span><span class="char">','</span><span class="special">)</span></code>
            as the previous examples did. This is ok due to C++ syntax rules of conversion.
            Spirit provides <code class="computeroutput"><span class="special">&lt;&lt;</span></code>
            operators that are overloaded to accept a <code class=