remove duplicate list elements
<p>I want to remove the duplicate elements in a list only when one element is repeated many times, like this:</p>

<pre><code>li = ['Human','Human','Human'] =&gt; li = ['Human']
</code></pre>

<p>but not when there are two or more different elements:</p>

<pre><code>li = ['Human','Monkey','Human', 'Human']
</code></pre>

<p>Many thanks in advance.</p>
