find(item, comparator = this.compare) {
    const foundItemIndices = [];

    for (let itemIndex = 0; itemIndex < this.heapContainer.length; itemIndex += 1) {
      if (comparator.equal(item, this.heapContainer[itemIndex])) {
        foundItemIndices.push(itemIndex);
      }
    }

    return foundItemIndices;
  }
@param {*} item
@param {Comparator} [comparator]
@return {Number[]}