function defaultComparator(a, b) {
    return a > b ? 1 : a < b ? -1 : 0;
}
Compares its two arguments for order.
@param a The first element to be compared.
@param b The second element to be compared.
@return A negative number, zero, or a positive number as the first
    argument is less than, equal to, or greater than the second.