vlib/v/parser/tests/for_in_mut_index_of_array.vv:3:6: error: index of array or key of map cannot be mutated
    1 | fn main() {
    2 |     mut m := [1, 2, 3]
    3 |     for mut i, _ in m {
      |         ~~~
    4 |         println(i)
    5 |     }
