title: Deep copy of a dict in python
body: <p>I would like to make a deep copy of a <code>dict</code> in python. Unfortunately the <code>.deepcopy()</code> method doesn't exist for the <code>dict</code>. How do I do that?</p>
  
  <pre><code>&gt;&gt;&gt; my_dict = {'a': [1, 2, 3], 'b': [4, 5, 6]}
  &gt;&gt;&gt; my_copy = my_dict.deepcopy()
  Traceback (most recent calll last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  AttributeError: 'dict' object has no attribute 'deepcopy'
  &gt;&gt;&gt; my_copy = my_dict.copy()
  &gt;&gt;&gt; my_dict['a'][2] = 7
  &gt;&gt;&gt; my_copy['a'][2]
  7
  </code></pre>
  
  <p>The last line should be <code>3</code>.</p>
  
  <p>I would like that modifications in <code>my_dict</code> don't impact the snapshot <code>my_copy</code>.</p>
  
  <p>How do I do that? The solution should be compatible with Python 3.x.</p>