title: Python code to accept many different formats of US phone numbers?
body: <p>I'm reading in lots of user entered data that represent phone numbers from files.  They are all slightly entered in differently:</p>
  
  <pre>
  5555555555
  555-555-5555
  555-555/5555
  1555-555-5555
  etc...
  </pre>
  
  <p>How could I easily parse in all of these phone numbers in Python and produce a canonical output like:
  555-555-5555?</p>