title: python: how to find consecutive pairs of letters by regex?
body: <p>I want to find words that have consecutive letter pairs using regex.
  I know for just one consecutive pair like <strong>zoo (oo), puzzle (zz), arrange (rr)</strong>, it can be achieved by <code>'(\w){2}'</code>. But how about</p>
  
  <ul>
  <li>two consecutive pairs:   <strong>committee (ttee)</strong>  </li>
  <li>three consecutive pairs:   <strong>bookkeeper (ookkee)</strong> </li>
  </ul>
  
  <p>edit:</p>
  
  <ul>
  <li><code>'(\w){2}'</code> is actually wrong, it finds any two letters instead of a double letter pair.</li>
  <li>My intention is to find the <strong>words</strong> that have letter pairs, not the pairs.</li>
  <li>By 'consecutive', I mean there is no other letter between letter pairs. </li>
  </ul>