I apologize if this is a duplicate question, but I couldn't find another issue about this.  It's hard to search on 're'.

In 3.7, I get a deprecation warning when using a regular string with re escape characters:
>>> s = '123abcd'
>>> re.findall('\d', s)
<stdin>:1: DeprecationWarning: invalid escape sequence \d
['1', '2', '3']

Of course, this works:
>>> s = '123abcd'
>>> re.findall(r'\d', s)
['1', '2', '3']


I know that the documentation strongly suggests using raw strings with re, but I didn't see anywhere mentioning that it would be a requirement.  I would think this would break a lot of 're' code.