title: "declared and not used" Error
body: <p>I get this error saying that I'm not using a variable&hellip; but to my noob eyes, it looks like I am:</p>
  
  <pre><code>func Sqrt(x float64) float64 {
  
      z := float64(x);
  
      for i := 0; i &lt; 10; i++ {
          z := z - (z*z - x) / (2 * z);
      }
  
      return z;
  }
  </code></pre>
  
  <p>Can anyone point out what I'm missing about the language? I think it has to do with <code>=</code> vs. <code>:=</code> and scoping, but I'm not sure.</p>