> <span class="identifier">Context</span><span class="special">,</span> <span class="identifier">Skipper</span><span class="special">&gt;</span>
            <span class="identifier">fail_function</span><span class="special">;</span>

        <span class="identifier">Iterator</span> <span class="identifier">iter</span> <span class="special">=</span> <span class="identifier">first</span><span class="special">;</span>
        <span class="identifier">fail_function</span> <span class="identifier">f</span><span 