package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
	n := 0
	history := []int{0, 1}
	return func() int {
		defer func() { n += 1 }()

		if n < 2 {
			return history[n]
		} else {
			ret := history[0] + history[1]
			history[0] = history[1]
			history[1] = ret
			return ret
		}
	}
}

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