A Tour of Go Exercise: Fibonacci closure

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
    before := 0
    now := 0
    return func() int {
        if before == 0 {
            before++
            return before
        }
        if now == 0 {
            now++
            return now
        }
        temp := now
        now = before + now
        before = temp
        return now 
    }
}

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