{motive_2 : Lean.IR.FnBody → Sort u} →
  (t : Lean.IR.FnBody) →
    ((x : Lean.IR.VarId) →
        (ty : Lean.IR.IRType) → (e : Lean.IR.Expr) → (b : Lean.IR.FnBody) → motive_2 (Lean.IR.FnBody.vdecl x ty e b)) →
      (Nat.hasNotBit 1 t.ctorIdx → motive_2 t) → motive_2 t