{α β : Type} →
  {motive : Std.Internal.Async.IO.AsyncStream α β → Sort u} →
    ((next : α → Std.Internal.IO.Async.Selector β) → (stop : α → IO Unit) → motive { next := next, stop := stop }) →
      (t : Std.Internal.Async.IO.AsyncStream α β) → motive t