/span> option</span>)</span> <span class="arrow">&#45;&gt;</span></span> <span><span class="type-var">'a</span> option</span> * <span><span class="type-var">'a</span> <a href="#type-t">t</a></span></span></code></div><div class="spec-doc"><p><code>find_update k f m</code> is <code>(found, m')</code> where <code>found</code> is <code>find k m</code> and <code>find k m'</code> is <code>f found</code> and <code>find h m'</code> is <code>find h m</code> for all other <code>h</code>.</p></div></div><div class="o