error[[E0053]](https://doc.rust-lang.org/nightly/error_codes/E0053.html): method `foo` has an incompatible type for trait
 --> src/lib.rs:8:29
  |
8 |     async fn foo(&mut self) {}
  |                             ^ expected associated type, found future
  |
note: type in trait
 --> src/lib.rs:4:28
  |
4 |     async fn foo(&mut self);
  |                            ^
  = note: expected signature `fn(&mut T) -> impl Future<Output = ()>`
             found signature `fn(&mut T) -> impl Future<Output = ()>`