Show suggestions in error messages in Python 3.10

[tirkarthi]

Fixes #13445

[Carreau]

Hum , I think we might be able to get something better with

def structured_traceback(...):
    from difflib import get_close_matches
    get_close_matches(value.name, dir(value.obj)

And re-implemented the match logic (even if slightly different). That way we can properly highlight tokens.

[aroberge]

I believe that the suggestion to use difflib would only work for AttributeError cases but not for NameError (where the misspelled name can be found in the local or global scope).

[aroberge]

Furthermore, difflib gives different results from those given by cPython.

>>> import math
>>> math.Pi
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'math' has no attribute 'Pi'. Did you mean: 'pi'?
>>> from difflib import get_close_matches
>>> get_close_matches('Pi', dir(math))
[]

[tirkarthi]

CPython has done several tweaks to get better results. IMO, it's better to use the suggestions from the compiler itself to avoid any discrepancy and to avoid reimplementing/maintaining the algorithm.

python/cpython#25412
python/cpython#25443
python/cpython#25460
python/cpython#25584
python/cpython#25776