Vasya Pikulev

**I'm submitting a ...** ``` [x] bug report => search github for a similar issue or PR before submitting [ ] feature request [ ] support request => Please do...

Context: https://go.dev/tour/methods/21 My proposal is to change line 16 from this: ```fmt.Printf("b[:n] = %q\n", b[:n])``` to this: ```fmt.Printf("b[:%v] = %q\n", n, b[:n])``` This change will more clearly display the length...