title: convert a string 2d list back to 2d list in python
body: <p>I just started playing around with python.
  I know that we can convert any list to a string using str()
  Like:</p>
  
  <pre><code>&gt;&gt;&gt; l = [[1,1] , [2,2] , [3,3]]
  &gt;&gt;&gt; l
  [[1, 1], [2, 2], [3, 3]]
  &gt;&gt;&gt; type(l)
  &lt;type 'list'&gt;
  &gt;&gt;&gt; str(l)
  '[[1, 1], [2, 2], [3, 3]]'
  &gt;&gt;&gt; list_string = str(l)
  &gt;&gt;&gt; list_string
  '[[1, 1], [2, 2], [3, 3]]'
  &gt;&gt;&gt; type(list_string)
  &lt;type 'str'&gt;
  </code></pre>
  
  <p>Is there a way to convert list_string back to a 2d list ??
  Basically, is there a function to convert this back to its original form ?</p>
  
  <pre><code>old_list = magic_conversion_func(list_string)
  
  &gt;&gt;&gt;old_list
  [[1, 1], [2, 2], [3, 3]]
  </code></pre>
  
  <p>I tried list() but that converts every char in the string to a new list element.</p>
  
  <pre><code>&gt;&gt;&gt; list(list_string)
  ['[', '[', '1', ',', ' ', '1', ']', ',', ' ', '[', '2', ',', ' ', '2', ']', ',', ' ', '[', '3', ',', ' ', '3', ']', ']']
  </code></pre>
  
  <p>that is not what I want</p>