Actions that can be performed by mock handlers.
type 'a t = [ | `Return of 'a(*Immediately return a value
*)| `Raise of exn(*Raise an exception
*)| `Await of 'a Eio.Promise.or_exn(*Wait for a promise to resolve
*)| `Yield_then of 'a t| `Run of unit -> 'a(*Run any code you like.
*)
]val run : 'a t -> 'arun t performs action t and returns the result.