ser</span> <span class="special">=</span>
    <span class="comment">// we pass our error handler to the parser so we can access</span>
    <span class="comment">// it later in our on_error and on_sucess handlers</span>
    <span class="identifier">with</span><span class="special">&lt;</span><span class="identifier">error_handler_tag</span><span class="special">&gt;(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">ref</span><span class="special">(</span><span 