[Python-projects] pylint false positive: Unused argument/variable on "-="

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    Maarten> The "setA" variable itself is indeed unused. But the value of
    Maarten> the object that "setA" refers to is most likely used somewhere
    Maarten> outside this function.  For example:

I'd still argue that the warning will catch errors and is still useful.
pylint can't tell whether setA is immutable or not, so it can't tell if the
-= operator has side effects.

    Maarten> a = set(range(10))
    Maarten> exclude(a, set(range(5, 15)))
    Maarten> print a

What if I called it like this?

    exclude(4, 1)

?  That's a perfectly legal, though somewhat silly, way to call exclude().
In fact, when you originally presented just the exclude function without an
example, I saw the -= operator and immediately thought "ah, numbers".

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