vlib/v/checker/tests/wrong_fn_init_err.vv:4:7: error: functions must be defined, not instantiated like structs
    2 | 
    3 | fn main() {
    4 |     a := MyCallback{}
      |          ~~~~~~~~~~~~
    5 |     println(a)
    6 | }
vlib/v/checker/tests/wrong_fn_init_err.vv:4:7: error: type `MyCallback` is private
    2 | 
    3 | fn main() {
    4 |     a := MyCallback{}
      |          ~~~~~~~~~~~~
    5 |     println(a)
    6 | }