cial">&amp;</span> <span class="special">)</span> <span class="special">{</span> <span class="keyword">return</span> <span class="keyword">true</span><span class="special">;</span> <span class="special">}</span>
        <span class="keyword">bool</span> <span class="identifier">on_double</span><span class="special">(</span> <span class="keyword">double</span><span class="special">,</span> <span class="identifier">string_view</span><span class="special">,</span> <span class="identifier">error_code</span><spa