feat(rules): Add rule to check for mutations of loop iterator

[mimre25]

This implements a POC for #445.

I opted to go the route of alerting for any mutations of a loop iterator.

Note:
I picked B999 temporarily, not sure how the numbers are picked.
Also, I'm very much open to change the error message.

Would be happy if you could give this a review @cooperlees 🙂

[cooperlees]

Many thanks for this. Looks good. I like this starting point.

Can you please:

• Lets go with b038
• Add more detailed few lines explanation into READNE.rst

[cooperlees]

Many thanks for your contribution!

Will get a release our next week.

[sahuagin]

I have an example for a false positive (I hope), if it's desired.
Setup. A CSV file as input with the first item in each row being an index number.

        id_pos = 0
        # lf is LogFile not LazyFrame
        lf = self._logger
        with self.rlock:
            lf.seek(0, 0)
            cpos = lf.tell()
            for line in lf:
                if len(line.strip()) == 0:
                    continue
                sl = line.split(b",", 1)
                self._mapper[sl[id_pos]] = cpos
                cpos = lf.tell()

Desired behavior is to find all indexes and record the file position where they start.
This just started getting flagged, which led me here. There are 4 more flags in the same file,
tell()
seek() x2
write()

[JelleZijlstra]

@sahuagin thanks for the report, #453 should fix this.