title: How to access tags like `sphinx-build -t abc` in `conf.py`?
body: <p>According to Sphinx' documentation there is a <code>tags</code> object available in <code>conf.py</code> (<a href="https://www.sphinx-doc.org/en/master/usage/configuration.html#conf-tags" rel="nofollow noreferrer">master</a>). However, I get: <code>AttributeError: 'NoneType' object has no attribute 'has'</code></p>
  <p><code>conf.py</code>:</p>
  <pre class="lang-py prettyprint-override"><code>if tags.has('abc'):
  </code></pre>
  <p><code>pip list</code>:</p>
  <pre><code>Package      Version
  ------------ ---------
  Sphinx       5.0.2
  </code></pre>
  <p>How to access tags like <code>sphinx-build -t abc</code> in <code>conf.py</code>?</p>