how to go back to matching parenthesis in python-mode?

[edgar]

Hi!

I would like to know if you can help me, please. I have this MWE 
(minimally working example):

    a = sum([val for val in range(10)])

If I set the point (cursor) at the end of the line and type `C-M b' 
(`backward-sexp'), I would expect to go back to the matching parenthesis 
next to `sum', but it takes me to the beginning of the line.

How can I go back to the matching parenthesis? Thank you

GNU Emacs 27.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.27, 
cairo version 1.17.4) of 2021-03-26
python.el:
;; URL: https://github.com/fgallina/python.el
;; Version: 0.28

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