∀ {α : Type u_1} {β : Type u_2} {cmp : α → α → Ordering} {t₁ : Std.TreeMap α β cmp} {k : α} (x : α)
  (motive : x ∈ t₁ ∧ cmp x k = Ordering.gt → Prop) (x_1 : x ∈ t₁ ∧ cmp x k = Ordering.gt),
  (∀ (h₁ : x ∈ t₁) (h₂ : cmp x k = Ordering.gt), motive ⋯) → motive x_1