What's the best way to format a phone number in Python?

for library: phonenumbers (pypi, source)

Python version of Google's common library for parsing, formatting, storing and validating international phone numbers.

The readme is insufficient, but I found the code well documented.

Seems like your examples formatted with three digits groups except last, you can write a simple function, uses thousand seperator and adds last digit:

>>> def phone_format(n):                                                                                                                                  
...     return format(int(n[:-1]), ",").replace(",", "-") + n[-1]                                                                                                           
... 
>>> phone_format("5555555")
'555-5555'
>>> phone_format("5555555")
'555-5555'
>>> phone_format("5555555555")
'555-555-5555'
>>> phone_format("18005555555")
'1-800-555-5555'

Here's one adapted from utdemir's solution and this solution that will work with Python 2.6, as the "," formatter is new in Python 2.7.

def phone_format(phone_number):
    clean_phone_number = re.sub('[^0-9]+', '', phone_number)
    formatted_phone_number = re.sub("(\d)(?=(\d{3})+(?!\d))", r"\1-", "%d" % int(clean_phone_number[:-1])) + clean_phone_number[-1]
    return formatted_phone_number