∀ {α : Type u_1} {p : α → Prop} (a : Batteries.RBNode α) (x : α) (b : Batteries.RBNode α)
  (motive : Batteries.RBNode.All p (Batteries.RBNode.node Batteries.RBColor.black a x b) → Prop)
  (hl : Batteries.RBNode.All p (Batteries.RBNode.node Batteries.RBColor.black a x b)),
  (∀ (hx : p x) (ha : Batteries.RBNode.All p a) (hb : Batteries.RBNode.All p b), motive ⋯) → motive hl