∀ {m : Type w → Type w'} {α : Type u} {β : Type v} [inst : Monad m] [LawfulMonad m] {x : Std.Iterators.HetT m α}
  {f : α → Std.Iterators.HetT m β}, (x.bind f).Property = fun b => ∃ a, x.Property a ∧ (f a).Property b