package main

import (
	"fmt"
)

func fib() func() int {
	a, b := 0, 1
	return func() int {
		a, b = b, a+b
		return b
	}
}

func main() {
	f := fib()
	fmt.Println("This Fibonacci sequense < 10000")
	for x := f(); x < 10000; x = f() {
		fmt.Println(x)
	}
}