∀ {α : Type u} {β : α → Type v} {m : Type w → Type w'} [inst : Monad m] (f : (a : α) → β a → m PUnit.{w + 1})
  (as : Std.DHashMap.Internal.AssocList α β),
  Std.DHashMap.Internal.AssocList.forM f as = Std.DHashMap.Internal.AssocList.foldlM (fun x => f) PUnit.unit as