title: Printed length of a string in python
body: <p>Is there any way to find (even a best guess) the "printed" length of a string in python?  E.g. 'potaa\bto' is 8 characters in <code>len</code> but only 6 characters wide printed on a tty.  </p>
  
  <p>Expected usage:</p>
  
  <pre><code>s = 'potato\x1b[01;32mpotato\x1b[0;0mpotato'
  len(s)   # 32
  plen(s)  # 18
  </code></pre>