title: Python re.sub(): how to substitute all 'u' or 'U's with 'you'
body: <p>I am doing some text normalization using python and regular expressions. I would like to substitute all 'u'or 'U's with 'you'. 
  Here is what I have done so far:</p>
  
  <pre><code>import re
  text = 'how are u? umberella u! u. U. U@ U# u '
  print re.sub (' [u|U][s,.,?,!,W,#,@ (^a-zA-Z)]', ' you ', text)
  </code></pre>
  
  <p>The output I get is:</p>
  
  <pre><code>how are you  you berella you  you  you  you  you  you
  </code></pre>
  
  <p>As you can see the problem is that 'umberella' is changed to 'berella'. Also I want to keep the character that appears after a 'u'. For example I want 'u!' to be changed to 'you!'. Can anyone tell me what I am doing wrong and what is the best way to write the regular expression? </p>