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 `fn speak(x main.Animal, s string)`
         main.Cat has `fn speak(c main.Cat, 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 `fn speak(x main.Animal, s string)`
         main.Cat has `fn speak(c main.Cat, s &string)`
vlib/v/checker/tests/unimplemented_interface_e.vv:13:6: error: `Cat` does not implement interface `Animal`, cannot cast `Cat` to interface `Animal`
   11 | fn main() {
   12 |     foo(Cat{})
   13 |     _ = Animal(Cat{})
      |         ~~~~~~~~~~~~~
   14 | }
