title 28 29 in python

1>>> import re
2>>> def titlecase(s):
3...     return re.sub(rb"[A-Za-z]+('[A-Za-z]+)?",
4...                   lambda mo: mo.group(0)[0:1].upper() +
5...                              mo.group(0)[1:].lower(),
6...                   s)
7...
8>>> titlecase(b"they're bill's friends.")
9b"They're Bill's Friends."
10