My answer of "a tour of Go #44( http://go-tour-jp.appspot.com/#44 )"

gotour_41.go

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
	now, next := 1, 0
	return func() int {
		new_now, new_next := next, now+next
		now, next = new_now, new_next
		return next
	}
}

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

// result
//1
//1
//2
//3
//5
//8
//13
//21
//34
//55