Talk is cheap.

func Fibonacci(n int) int {
    if n <= 1 {
        return n
    } else {
        return Fibonacci(n - 1) + Fibonacci(n - 2)
    }
}

func Fibonacci(n int) int {
    res := []int{0, 1, 1}
    for i := 0; i < n; i++ {
        res[0], res[1], res[2] = res[1], res[2], res[1] + res[2]
    }
    if n <= 2 {
        return res[n]
    } else {
        return res[0]
    }
}

func Fibonacci(n int) int {
    a, b := 0, 1
    for ; n > 0; n-- {
        a, b = b, a + b
    }
    return a
}