_greater(i, j) {
        return this._comparator(this._heap[i], this._heap[j]);
    }
Check if the element at index `i` is greater than the element at index `j`.
@param {number} i The index of the first element to compare.
@param {number} j The index of the second element to compare.
@returns {boolean} `true` if the element at index `i` is greater than the element at index `j`, `false` otherwise.
@private