vlib/v/checker/tests/incorrect_for_in_name_variable.vv:3:6: error: variable name `_aa` cannot start with `_`
    1 | fn main() {
    2 |     a := [1,2,3]
    3 |     for _aa in a {
      |         ~~~
    4 |         println(_aa)
    5 |     }