package main

import "fmt"

func main() {
    list := []int{31, 41, 59, 26, 53, 58, 97, 93, 23, 84}
    fmt.Println("unsorted:", list)

    quicksort(list)
    fmt.Println("sorted!  ", list)
}

func quicksort(a []int) {
    var pex func(int, int)
    pex = func(lower, upper int) {
        for {
            switch upper - lower {
            case -1, 0: