title: cannot set properly the dict value inside dict
body: <p>I cannot set the individual value inside the nested dict as below. Normally I want to set only EntireMaze[(0,1)]['east'] but it sets all 'east' keys. Any idea ?</p>
  
  <pre><code>cell = {'east' : 0, 'south' : 0}
  EntireMaze = {}
  
  height = 2
  width = 3
  
  for row in range(0,height):
      for col in range(0,width):
          EntireMaze[(row,col)] = cell
  
  print EntireMaze
  EntireMaze[(0,1)]['east'] = 1
  print EntireMaze
  </code></pre>
  
  <p>Output is :</p>
  
  <pre><code>&gt;&gt;&gt; 
  {(0, 1): {'east': 0, 'south': 0}, (1, 2): {'east': 0, 'south': 0}, (0, 0): {'east': 0, 'south': 0}, (1, 1): {'east': 0, 'south': 0}, (1, 0): {'east': 0, 'south': 0}, (0, 2): {'east': 0, 'south': 0}}
  
  {(0, 1): {'east': 1, 'south': 0}, (1, 2): {'east': 1, 'south': 0}, (0, 0): {'east': 1, 'south': 0}, (1, 1): {'east': 1, 'south': 0}, (1, 0): {'east': 1, 'south': 0}, (0, 2): {'east': 1, 'south': 0}}
  </code></pre>