Arrow functions are not IIFE. This is just their syntax. If they are one line expressions they don't need return. But if they contain several lines of code, then they need return statement and curly braces around code block.

Does this work without the return statement because arrow functions are 'immediately invoked functions?'

Almost too good to be true (possible)!

I had the same problem. Needed a few drinks until I saw the solution.

nice

Nice kata,
Whiskey typo took up time

a string specifying a logical operator: "AND", "OR", "XOR"

Wasn't that there already?

Ah, it was unclear if op was a string or the actual logical operator. It's passsed as a string.

Woah that's cool. I didn't know argument could be asigned to a function and the function would be performed on it.

SCREAM += "Pa!"; is a nice touch.

The addition assignment operator scared me because I thought it'd return "Pa!" more than the one time it should be. The rest of your code takes care of that though. Nicely done.

I got an error that expected 'good luck' be returned. How does this account for that?