"input:" and "output:" there were added by NitOwl007, that seems Python and the error message would be like this: [1, 2, 4] should equal [1, 2, 4, 8, 16]

what language produces such message? it's indeed confusing and could use some improvements.

No, the input is a single number, the first one of those values is what your function returned instead of the expected one (the second value).

I'm confused, "input: [1, 2, 4] should equal output: [1, 2, 4, 8, 16]" so does that mean you can input several numbers?

Yeahhhh I feel like I'm missing something