title: Convert values of a list in dictionary to upper/lower case
body: <p>I have a dictionary in <code>python</code> like below</p>
  
  <pre><code>my_dict = {u'customer': [u'GS808E', u'GS810EMX'], u'tablets': [u'Apple IPAD PRO', u'Apple IPAD MINI', u'IPAD'], u'gaming_consoles': [u'SONY PLAYSTATION 4', u'XBOX ONE S', u'PLAYSTATION'], u'range_of_days': 14 }
  </code></pre>
  
  <p>I want to convert all the <code>values</code> in this <code>dictionary</code> to <code>lowercase</code> or <code>uppercase</code></p>
  
  <p>I have done like below.</p>
  
  <pre><code>new_dict = {k:[i.lower() for i in v] for k,v in my_dict.items()}
  </code></pre>
  
  <p>I am getting the below error in <code>Python 2.7</code></p>
  
  <pre><code>Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "&lt;stdin&gt;", line 1, in &lt;dictcomp&gt;
  TypeError: 'int' object is not iterable
  </code></pre>