Python version 3.10.0a7 added a more informative error message for:

>>> f"{**k}"
  File "<stdin>", line 1
    (**k)
     ^
SyntaxError: f-string: can't use double starred expression here

Previously, the message was simply "SyntaxError: invalid syntax".  So, this change is certainly a welcome addition.

However, as far as I can tell, starting with Python 3.8, all previous uses of "can't" in error messages were replaced by "cannot".  Although it is an extremely minor point, it might be preferable for consistency to replace "can't" by "cannot" in this new error message.

We can change the wording to `cannot` in order for all of the error messages to be consistent. Would you like to propose a PR, Andre?

Not all "can't" in error messages were replaced by "cannot".

$ find Parser Python Objects Modules -name '*.[ch]' | xargs egrep '".*[Cc]an'\''t.*"' | wc -l
181
$ find Parser Python Objects Modules -name '*.[ch]' | xargs egrep '".*[Cc]annot.*"' | wc -l
247

$ find Lib -name '*.py' | xargs egrep '(["'\'']).*[Cc]an'\''t.*\1' | wc -l
239
$ find Lib -name '*.py' | xargs egrep '(["'\'']).*[Cc]annot.*\1' | wc -l
602

$ find Doc -name '*.rst' | xargs egrep '[Cc]an'\''t' | wc -l
180
$ find Doc -name '*.rst' | xargs egrep '[Cc]annot' | wc -l
482

Since all the messages I track so far (https://github.com/aroberge/friendly/blob/master/friendly/syntax_errors/message_analyzer.py) had been changed when going from 6.7 to 3.8, I had (incorrectly) assumed that all such error messages been changed to use cannot instead of can't.  However, based on Serhyi's search, I gather that this is not the case and this specific issue can probably be closed as being irrelevant.

Yeah, I do not think anyone cares. :-)