A backslash-character pair that is not a valid escape sequence generates a DeprecationWarning since Python 3.6. In Python 3.8 it generates a SyntaxWarning instead.
Python 3.6.8 (tags/v3.6.8:3c6b436a57, Dec 24 2018, 00:16:47) [MSC v.1916 64 bit (AMD64)] on win32
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>>> from wordnik import swagger
C:\Program Files\Python36\lib\site-packages\wordnik\swagger.py:132: DeprecationWarning: invalid escape sequence \[
match = re.match('list\[(.*)\]', objClass)
C:\Program Files\Python36\lib\site-packages\wordnik\swagger.py:167: DeprecationWarning: invalid escape sequence \[
match = re.match('list\[(.*)\]', attrType)
Changed in version 3.6: Unrecognized escape sequences produce a DeprecationWarning.
Changed in version 3.8: Unrecognized escape sequences produce a SyntaxWarning. In some future version of Python they will be a SyntaxError.
https://docs.python.org/3.8/whatsnew/3.8.html
https://docs.python.org/3.6/whatsnew/changelog.html, https://bugs.python.org/issue27364, https://hg.python.org/cpython/rev/38802c38cfe1, https://github.com/python/cpython/commit/110b6fecbbb86143a4acb568f50eab2c870e7d34
https://docs.python.org/3.8/reference/lexical_analysis.html
https://bugs.python.org/issue32912, https://github.com/python/cpython/pull/9652, https://github.com/python/cpython/commit/6543912c90ffa579dc4c01e811f9609cf92197d3