It was an 1:1 interview. I was asked to extract some numbers out from a nested list. For example {{11,2,3},4,null,{1},{4,null,3}}. I was using a nested loop to save those numbers in a new array. So that it could be easy to get any of them out. But I'm sure there would have a simpler way. As time was limited, I didnt figure it out in the interview.