Type Annotations With Multi-Dimensional Array

/*
  Type Annotations With Multidimensional Arrays
*/

let arrayOne: number[] = [1, 2, 3, 4, 5];
let arrayTwo: string[] = ["A", "B", "C"];
let arrayThree: (string | number)[] = [1, 2, 3, 4, "A", "B", "C"];

let arrayFour: (string | number | string[] | boolean)[] = [1, 2, 3, 4, "A", "B", ["C", "D"], true, false];