This defines a nested mutable reference.
```rs use refmutnlines::refmutnlines;
fn main() { let mut data = [[0u8; 3]; 4]; let refdata: &mut [&mut [u8]] = refmutn_lines!(data, 4); } ```
work as
rs
let _ref_data: &mut [&mut [u8]] = {
let [ref mut a0, ref mut a1, ref mut a2, ref mut a3] = data;
&mut[a0, a1, a2, a3]
}