ss="arrow">&#45;&gt;</span></span> <span><span>(<a href="#type-key">key</a> * <span class="type-var">'a</span>)</span> <a href="../../IContainer/index.html#type-singleton_or_more">IContainer.singleton_or_more</a></span></span></code></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-pp_key"><a href="#val-pp_key" class="anchor"></a><code><span><span class="keyword">val</span> pp_key : <span><a href="../../PrettyPrintable/index.html">IStdlib.PrettyPrintable</a>.F.formatter <span class