闭包实现Fibonacci

package main

import "fmt"

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

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