package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
    x := 0
    y := 1
    z := 0
    return func() int {
        z, x, y = x, y, x + y
        if z == 0 {
            return 0
        }
        return z
    }
}

func main() {
	f := fibonacci()
	for i := 0; i < 10; i++ {
		fmt.Println(f())
	}
}