Detect unused arguments

[cjerdonek]

A related feature that could be useful would be to detect "dead arguments," or function arguments not used by the function body.

Here is an example of a dead argument found in pip: pypa/pip#7015

[asottile]

definitely doable! potentially has the same issue as inheritance methods for false positives but probably still worth it

[cjerdonek]

false positives

Yeah, but just seeing the list of possibilities could help!

[asottile]

#24 is a first stab at this, it doesn't actually detect the particular case because dead doesn't know about scopes yet (it assumes all symbols are global for now)