/span></span> <span class="type-var">'b</span> * <span><span class="type-var">'c</span> <a href="#type-t">t</a></span></span></code></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-is_singleton_or_more"><a href="#val-is_singleton_or_more" class="anchor"></a><code><span><span class="keyword">val</span> is_singleton_or_more : 
  <span><span><span class="type-var">'a</span> <a href="#type-t">t</a></span> <span class="arrow">&#45;&gt;</span></span>
  <span><span>(<a href="#type-key">k