code: function swapArrayElements(items, indexFrom, indexTo) {
    var item = items[indexTo];
    items[indexTo] = items[indexFrom];
    items[indexFrom] = item;
    return items;
  }
docs: * Helper functions - they are decoupled because of testability 
  @param {array} items
  @param {number} indexFrom
  @param {number} indexTo
  @returns {array}