title: Add a folder to the Python library path, once for all (Windows)
body: <p>I use</p>
  
  <pre><code>sys.path.append('D:/my_library_folder/')
  import mymodule
  </code></pre>
  
  <p>in order to import some module.</p>
  
  <p>How to add <em>permanently</em> this folder <code>D:/my_library_folder/</code> to the Python library path, so that I will be able to use <strong>only</strong></p>
  
  <pre><code>import mymodule
  </code></pre>
  
  <p>in the future?</p>
  
  <p>(Even after a reboot, etc.)</p>