title: Python compare two strings and check how many chars they have in common
body: <p>I'm just wondering how I can check how many chars two string have in common.
  For example if I have "car" and "cars", the result should be 3. </p>
  
  <p>Anybody a clue?</p>
  
  <p>Cheers and thanks in advance</p>
  
  <p>Max</p>