title: Match 'mm/yyyy' not 'mm/dd/yyyy' using Python Regex
body: <p>I want to match date using Python regular expression. I have 05/21/1990 (mm/dd/yyyy) and 01/1990 (mm/yyyy). How can I match the second one only. I tried following code</p>
  
  <pre><code>&gt;&gt;&gt; re.search（r'\b\d{1,2}/\d{2,4}\b', '5/1/1990').group(0)
      '1/1990'
  </code></pre>
  
  <p>But it doesn't work. Can someone explain why? Isn't '\b' represent the word boundary? What is a better way to match 'mm/yyyy'?</p>