title: What happens when I modify the source code of a running python program?
body: <h1>file_a.py</h1>
  
  <pre><code>while 1:
      print 1
  </code></pre>
  
  <p>When I remove, rename, even change "print 1" to "print 2",
  it is still running with printing 1.</p>
  
  <p>Does it mean python runs with pyc files? What kind of feature of interpreter works here?</p>