title: what does the __file__ variable mean/do?
body: <pre class="lang-py prettyprint-override"><code>import os
  
  A = os.path.join(os.path.dirname(__file__), '..')
  
  B = os.path.dirname(os.path.realpath(__file__))
  
  C = os.path.abspath(os.path.dirname(__file__))
  </code></pre>
  <p>I usually just hard-wire these with the actual path.  But there is a reason for these statements that determine path at runtime, and I would really like to understand the <code>os.path</code> module so that I can start using it.</p>