title: How to set a Python variable to 'undefined'?
body: <p>In Python 3,  I have a global variable which starts as "undefined".</p>
  
  <p>I then set it to something. </p>
  
  <p>Is there a way to return that variable to a state of "undefined"?</p>
  
  <p>@martijnpieters</p>
  
  <p>EDIT - this shows how a global variable starts in a state of undefined.</p>
  
  <pre><code>Python 2.7.5+ (default, Feb 27 2014, 19:37:08) 
  [GCC 4.8.1] on linux2
  Type "help", "copyright", "credits" or "license" for more information.
  &gt;&gt;&gt; x
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  NameError: name 'x' is not defined
  &gt;&gt;&gt; global x
  &gt;&gt;&gt; x
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  NameError: name 'x' is not defined
  &gt;&gt;&gt; 
  </code></pre>