Last time I used one, I was trying to get help writing a custom naming strategy for a Java ObjectMapper. Mostly written python in my career so just needed the broad strokes of it to be filled in.

It gave me some example code that looked plausible but in actuality was the exact inverse of how you are supposed to implement it. Took me like a day and a half to debug it; reckon I could have written it in an afternoon by going straight to the documentation.