vlib/v/checker/tests/unimplemented_interface_e.vv:12:6: error: `Cat` incorrectly implements method `speak` of interface `Animal`: expected `string`, not `&string` for parameter 1
   10 | 
   11 | fn main() {
   12 |     foo(Cat{})
      |         ~~~~~
   13 |     _ = Animal(Cat{})
   14 | }
Details: main.Animal has `speak(s string)`
vlib/v/checker/tests/unimplemented_interface_e.vv:13:6: error: `Cat` incorrectly implements method `speak` of interface `Animal`: expected `string`, not `&string` for parameter 1
   11 | fn main() {
   12 |     foo(Cat{})
   13 |     _ = Animal(Cat{})
      |         ~~~~~~~~~~~~~
   14 | }
Details: main.Animal has `speak(s string)`