∀ {α : Type u} {r : Std.Rio α} [inst : LT α] [inst_1 : DecidableLT α] [inst_2 : Std.PRange.Least? α]
  [inst_3 : Std.PRange.UpwardEnumerable α] [inst_4 : Std.PRange.LawfulUpwardEnumerable α]
  [Std.PRange.LawfulUpwardEnumerableLT α] [inst_6 : Std.PRange.LawfulUpwardEnumerableLeast? α]
  [inst_7 : Std.Rxo.IsAlwaysFinite α], r.toArray = #[] ↔ ¬Std.PRange.UpwardEnumerable.least < r.upper