∀ {α : Type v} {γ : Type u} {β : Type v} {m : Type w → Type x} [inst : Monad m] [LawfulMonad m] {δ : Type w}
  [inst_2 : Std.ToIterator (Std.Slice γ) Id α β] [inst_3 : Std.Iterator α Id β] [inst_4 : Std.IteratorLoop α Id m]
  [Std.LawfulIteratorLoop α Id m] [Std.Iterators.Finite α Id] {s : Std.Slice γ} {init : δ}
  {f : β → δ → m (ForInStep δ)}, forIn s.toArray init f = forIn s init f