∀ {motive : Lean.Elab.Term.Op.Tree✝ → Sort u} (t : Lean.Elab.Term.Op.Tree✝¹)
  (F_1 : (t : Lean.Elab.Term.Op.Tree✝²) → Lean.Elab.Term.Op.Tree.below✝ t → motive t),
  Lean.Elab.Term.Op.Tree.brecOn✝ t F_1 = F_1 t (Lean.Elab.Term.Op.Tree.brecOn.go✝ t F_1).2