title: python supervisord program dependency
body: <p>I have <code>[program:A]</code>, <code>[program:B]</code> in my supervisord.conf</p>
  
  <p><code>B</code> depend <code>A</code>, means:</p>
  
  <p><code>A</code> should start before <code>B</code>.</p>
  
  <p>How to ensure this by supervisor?</p>