0 <= m, n <= 10^15 m > n

Did the author mean m < n?

def xor_reduction(m, n):
...

test.assert_equals(xor_reduction(0, 9), 1)
test.assert_equals(xor_reduction(0, 1), 1)
test.assert_equals(xor_reduction(2, 5), 0)
...

Where is the 48 coming from? I don't get the solution.

True. Thank you

0 <= m, n <= 10^15 m > n

but, one of the tests is test.assert_equals(xor_reduction(1, 1), 1) with m=n

that works!

Thank you for the feedback. Done.

why wouldn't that be a duplicate, this time?

oh, 'just saw the difference, ok.

You're welcome, sorry it didn't work out. The difference would be minimal in that the lower bound simply isn't 0 anymore, so while it's not an exact duplicate, it's too close. Regardless, always check for duplicates as rigorously as possible, trying many different names.

Thank you!
I didn't find it when I searched for similar katas.
I've also made a similar one (not published yet) where you're given two ints and have to xor all ints between them, is it a duplicate as well?

Duplicate.