Example is incorrect

[swork1]

Describe the issue

The following example is incorrect. Running the following code gives me the output of
a -> [2, 2, 2, 2, 2, 3, 4]
b -> [2, 3, 13]

mut a := []int{len: 5, cap: 6, init: 2}
mut b := a[1..4]
a << 3
// no reallocation - fits in `cap`
b[2] = 13 // `a[3]` is modified
a << 4
// a has been reallocated and is now independent from `b` (`cap` was exceeded)
b[1] = 3 // no change in `a`
println(a) // `[2, 2, 2, 13, 2, 3, 4]`
println(b) // `[2, 3, 13]`

Updated code - requires the unsafe

mut a := []int{len: 5, cap: 6, init: 2}
mut b := unsafe { a[1..4] }
a << 3
// no reallocation - fits in `cap`
b[2] = 13 // `a[3]` is modified
a << 4
// a has been reallocated and is now independent from `b` (`cap` was exceeded)
b[1] = 3 // no change in `a`
println(a) // `[2, 2, 2, 13, 2, 3, 4]`
println(b) // `[2, 3, 13]`

Links

https://github.com/vlang/v/blob/master/doc/docs.md#array-slices