 class="token keyword">open </span><span class="token keyword">operator override </span><span class="token keyword">fun </span><a href="contains.html"><span class="token function">contains</span></a><span class="token punctuation">(</span><span class="parameters "><span class="parameter ">element<span class="token operator">: </span><a href="index.html">T</a><span class="token operator">?</span></span></span><span class="token punctuation">)</span><span class="token operator">: </span><a href="https://kotli