would it be clearer to have "is" with literal of type 'str'?

Note that types are often in `:

>>> 1+'d'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for +: 'int' and 'str'

But consistently with only double quotes, or only single quotes?

Thanks, I've added quotes to the types. I kept the phrase 'str' literal instead of literal of type 'str', since I found it a little easier to read and is similar to the way we just mention the types in the add example you give (instead of e.g. saying value of type 'int' and value of type 'str')

I'm happy with whatever quote type, let me know!

I had this originally, but it needed a forward reference / we know it's a Constant_kind so we could skip the switch :-)

I'll add it back!

Addressed, let me know if I should move the function instead

left gets updated in each iteration, but e->v.Compare.left is always the same thing. Is this correct?

Should we just check the first item before the loop and then here just look at right_expr?

I might be missing something, but bool left = check_is_arg(e->v.Compare.left); happens once outside the loop and it's only right that is updated in each iteration.

line 2296?

Ah, of course! Thank you so much, this is buggy. I added the fix and a test case to catch the issue.

I think we can't do the first item check before the loop since all comparators may not be is, e.g. x == 3 is y, but let me know if I'm missing something!