I think that's an error from the testing. Thank you for the aclaration.

Thank you.
I was really distracted with the error I got.

Your solution should return an int, but it returns a string.

I need some help with this problem. Does it mean than my code is wrong or the test is bugged? What should I do?

File "tests.py", line 6, in
test.expect(greek_comparator('alpha', 'beta') < 0, "result should be negative")
TypeError: '<' not supported between instances of 'str' and 'int'