You are very correct!
The current implmentation did not account for when number is equal 0

guy, you are Einstein

indeed, if you call makeNegative(0) it will be -0 :)

beautiful

You should check what the value of num is first. In this case, if it's less than 0 (already negative) you simply return as is. If it's greater than or equal to 0, you return the negative of it.

i tried just returning -num. how does your code work?

use num > -num as the condition to correct the negative 0

Nice and simple!

Ah, thanks! I didn't consider function order at the time and the fact that map could change a value so it wouldn't pass a filter later on.

It wouldn't hurt to add another smaller test to show this, or better yet, mention it in description that function order is important, and also that there can be multiple maps / filters and they can occur in any order.