My answer for http://go-tour-jp.appspot.com/#43

gistfile1.go

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
    a, b := 1, 1
    return func() int {
        tmp := a
        a = b
        b = tmp + b
        return tmp
    }
}

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