∀ {α : Type u} {cmp : α → α → Ordering} {m : Type w → Type w₂} [inst : Monad m] [inst_1 : LawfulMonad m]
  [inst_2 : Std.TransCmp cmp] (f f_1 : α → m PUnit.{w + 1}),
  f = f_1 → ∀ (t t_1 : Std.ExtTreeSet α cmp), t = t_1 → Std.ExtTreeSet.forM f t = Std.ExtTreeSet.forM f_1 t_1