entry</span> <span class="special">&amp;</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">default</span><span class="special">;</span>
    <span class="keyword">bool</span> <a class="link" href="basic_environment/entry_type.html#idp51467024-bb"><span class="identifier">empty</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
    <span class="keyword">void</span> <a class="link" href=