Extend slice length on the left : <p>I just started going through gotour, and encountered a question regarding slice defaults chapter.</p>

<pre><code>package main

import "fmt"

func main() {
    s := []int{2, 3, 5, 7, 11, 13}

    s = s[1:4]
    fmt.Println(s) // [3 5 7]
    fmt.Println(len(s)) // 3

    s = s[:4]  
   fmt.Println(s) // [3 5 7 11]
   fmt.Println(len(s)) // 4

}
</code></pre>

<p>I can extend the length of slice on the right by picking an index greater than or equal to previous slice length. e.g. <code>s[:4]</code> so I can reach entry <code>11</code>. But when I use<code>s[-1:]</code> to extend on the left and reach entry <code>2</code>, compiler gives me error <code>invalid slice index -1 (index must be non-negative)</code>.
Is it possible to extend the slice length on the left to reach entry <code>2</code> after <code>s=s[1:4]</code> executed?</p>
