title: Negation in Python
body: <p>I'm trying to create a directory if the path doesn't exist, but the ! (not) operator doesn't work. I'm not sure how to negate in Python... What's the correct way to do this?</p>
  
  <pre><code>if (!os.path.exists("/usr/share/sounds/blues")):
          proc = subprocess.Popen(["mkdir", "/usr/share/sounds/blues"])
          proc.wait()
  </code></pre>