</span></span> <span>string <span class="arrow">&#45;&gt;</span></span> string * string</span></code></div></div><div class="odoc-spec"><div class="spec module anchored" id="module-Set"><a href="#module-Set" class="anchor"></a><code><span><span class="keyword">module</span> <a href="Set/index.html">Set</a></span><span> : <span class="keyword">sig</span> ... <span class="keyword">end</span></span></code></div></div><div class="odoc-spec"><div class="spec module anchored" id="module-Map"><a href="#module-Map"