title: Django's general setup() function
body: <p>I was reading the Django <a href="https://docs.djangoproject.com/ja/1.9/topics/logging/#configuring-logging" rel="nofollow">logging docs</a> and came across this line:</p>
  
  <blockquote>
    <p>Logging is configured as part of the general Django setup() function. Therefore, you can be certain that loggers are always ready for use in your project code.</p>
  </blockquote>
  
  <p>Which <strong>general <code>setup()</code> function</strong> is being talked about here? 
  Does this function execute only once at startup, making it the best entry point hook to add custom code?</p>
  
  <p>How is it different from the <code>MyAppConfig</code> defined in <code>apps.py</code>. </p>