 rfind : <span><span class="label">sub</span>:string <span class="arrow">&#45;&gt;</span></span> <span>string <span class="arrow">&#45;&gt;</span></span> int</span></code></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-replace"><a href="#val-replace" class="anchor"></a><code><span><span class="keyword">val</span> replace : 
  <span><span class="optlabel">?which</span>:<span>[ `All <span>| `Left</span> <span>| `Right</span> ]</span> <span class="arrow">&#45;&gt;</span></span>
  <s