// A tuple type flows through a destructuring query.
type 
type Either2dOr3d = [number, number, (number | undefined)?]Either2dOr3d = [number, number, number?]

function 
function setCoordinate(coord: Either2dOr3d): voidsetCoordinate(
(parameter) coord: Either2dOr3dcoord: 
type Either2dOr3d = [number, number, (number | undefined)?]Either2dOr3d) {
  const [
const x: numberx, 
const y: numbery, z] = 
(parameter) coord: Either2dOr3dcoord
const z: number | undefined
}