pan><span class="special">).</span><span class="identifier">get</span><span class="special">();</span>
        <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">message</span> <span class="special">=</span> <span class="string">"Error! Expecting: "</span> <span class="special">+</span> <span class="identifier">x</span><span class="special">.</span><span class="identifier">which</span><span class="special">()</span> <span class="