go - "declared and not used" Error

Question

I get this error saying that I'm not using a variable… but to my noob eyes, it looks like I am:

func Sqrt(x float64) float64 {

    z := float64(x);

    for i := 0; i < 10; i++ {
        z := z - (z*z - x) / (2 * z);
    }

    return z;
}

Can anyone point out what I'm missing about the language? I think it has to do with = vs. := and scoping, but I'm not sure.

Answer 1

Waitting for answers