Given an array of integers, find the one that appears an odd number of times.

That's very clear to me. And you can look at the sample tests:

test.assert_equals(find_it([20,1,-1,2,-2,3,3,5,5,1,2,4,20,4,-1,-2,5]), 5)

5 appears 3 times, and the expected answer is 5, so, it's the integer, not the times it appears.

You need to return the value of the integer that appears an odd number of times.

I don't understand what we are supposed to return. Do we return the value of the integer that appears an odd number of times? Or do we return the number of times the odd integer appeared? This kata is very unclear.

well, looks like it is my mistake. I did not understood correctly the word odd

Well, for [18, 1, 7, 1, 1, 1, 18, 18, 7], 18 occurs 3 times (odd number). The other array seems impossible, unless you're modifying the input. (but if so, 3 occurs 7 times, so it's a valid answer)

incredible