title: Python list problem
body: <p>python:</p>
  
  <pre><code>m=[[0]*3]*2
  for i in range(3):
      m[0][i]=1
  
  print m
  </code></pre>
  
  <p>I expect that this code should print</p>
  
  <pre><code>[[1, 1, 1], [0, 0, 0]]
  </code></pre>
  
  <p>but it prints</p>
  
  <pre><code>[[1, 1, 1], [1, 1, 1]] 
  </code></pre>