static intersection(arrA, arrB) {
    let intersection = new Array();

    for (let i = 0; i < arrA.length; i++) {
      for (let j = 0; j < arrB.length; j++) {
        if (arrA[i] === arrB[j]) {
          intersection.push(arrA[i]);
        }
      }
    }

    return intersection;
  }
Returns an array containing the intersection between two arrays. That is, values that are common to both arrays.

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