Array.diagonal()
Array.diagonal(nthDiagonalIndex)
Extract the diagonal at nthDiagonalIndex (-ve for diagonals below the proper diagonal, and zero for the proper diagonal).
|4|.diagonal(0..2)
|4|.diagonal(0)
|4|.diagonal(-1..1)
Extract the diagonal at nthDiagonalIndex (-ve for diagonals below the proper diagonal, and zero for the proper diagonal).
|4|.diagonal(0..2)
|4|.diagonal(0)
|4|.diagonal(-1..1)