static merge(arrA, arrB) {
    let arr = new Array(arrA.length + arrB.length);

    for (let i = 0; i < arrA.length; i++) {
      arr[i] = arrA[i];
    }

    for (let i = 0; i < arrB.length; i++) {
      arr[arrA.length + i] = arrB[i];
    }

    return arr;
  }
Merges two arrays and returns the result. The first array will be appended to the second array.

@static
@param {Array} arrA An array.
@param {Array} arrB An array.
@returns {Array} The merged array.