n class="keyword">val</span> concat : <span><span class="label">sep</span>:string <span class="arrow">&#45;&gt;</span></span> <span><span>string list</span> <span class="arrow">&#45;&gt;</span></span> string</span></code></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-cat"><a href="#val-cat" class="anchor"></a><code><span><span class="keyword">val</span> cat : <span>string <span class="arrow">&#45;&gt;</span></span> <span>string <span class="arrow">&#45;&gt;</span></span> string<