title: BeautifulSoup - How to find a specific class name alone
body: <p>How to find the <code>li</code> tags with a specific class name but not others? For example:</p>
  
  <pre><code>...
  &lt;li&gt; no wanted &lt;/li&gt;
  &lt;li class="a"&gt; not his one &lt;/li&gt;
  &lt;li class="a z"&gt; neither this one &lt;/li&gt;
  &lt;li class="b z"&gt; neither this one &lt;/li&gt;
  &lt;li class="c z"&gt; neither this one &lt;/li&gt;
  ...
  &lt;li class="z"&gt; I WANT THIS ONLY ONE&lt;/li&gt;
  ...
  </code></pre>
  
  <p>the code:</p>
  
  <p><code>bs4.find_all ('li', class_='z')</code>
  returns several entries where there is a <code>"z"</code> and another class name.</p>
  
  <p>How to find the entry with the class name <code>"z"</code>, alone ?</p>