title: Python regular expression match not working
body: <p>I have written below given code to match a string of fixed length of 10 which contains all digits.</p>
  
  <pre><code>import re
  result=re.match("^d{10}$", u"5478512045")
  </code></pre>
  
  <p>But it returns None. I don't know why is it failing. Please correct me if I am doing anything wrong over here.</p>