static areSetsEqual(setA, setB) {
    if (setA.size !== setB.size) {
      return false;
    }

    for (let element of setA) {
      if (!setB.has(element)) {
        return false;
      }
    }

    return true;
  }
Checks whether or not two sets are equal (contain the same elements).

@param {Set<Number>} setA A set.
@param {Set<Number>} setB A set.
@returns {Boolean} A boolean indicating whether or not the two sets are equal.