title: python output unexpected behaviour
body: <p>Following program is used to sort a list</p>
  
  <pre><code>    for i in range(len(q)):
          for j in range(len(q)):
              if not (q[i] &lt; q[j]):
                  t = q[i]
                  q[i] = q[j]
                  q[j] = t
  </code></pre>
  
  <p>contents of q are : {-1 2 4}</p>
  
  <p>The output I get has one empty number like:</p>
  
  <p>4</p>
  
  <p>-1
  2</p>
  
  <p>i.e. extra number (empty) between 4 and -1. What am I doing wrong?</p>