a.swift

func f() {
        let max = range.product(range).maxWith { (topRow, leftCol) -> (Int) in
            return (0..<3).product(0..<3).map { rowOffset, colOffset in // (rowOffset: Int, colOffset: Int) -> (Int) in
                return scores[topRow + rowOffset][leftCol + colOffset]
            }.reduce(0, +)
        }
}