Prevent warnings on dict / list index lookup with destructuring assignment

[timmartin]

Type of Changes

	Type
✓	🐛 Bug fix

Description

The checkers unnecessary-list-index-lookup and unnecessary-dict-index-lookup have a check that the usage of the index isn't appearing on the left hand side of an assignment. So for example:

for key, val in my_dict:
    my_dict[key] = 'x'

should not be a warning. However, this checker was not catching the case where the assignment was part of a destructuring expression, so there was a false positive for:

for key, val in my_dict:
    (my_dict[key], _) = ('x', 1)

This has been fixed.

Closes #6788

[coveralls]

Pull Request Test Coverage Report for Build 2436051343

• 10 of 10 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.002%) to 95.523%

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Totals
Change from base Build 2433586834:	0.002%
Covered Lines:	16259
Relevant Lines:	17021

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💛 - Coveralls

[jacobtylerwalls]

Thanks for the speedy fix! Some trivial feedback.

[github-actions]

🤖 According to the primer, this change has no effect on the checked open source code. 🤖🎉This comment was generated for commit 7931c3f

[Pierre-Sassoulas]

Thank you @timmartin , it looks great, I also like the new named function that makes it easier to understand the conditions.