∀ {α : Type u_1} {r : Std.Rio α} [inst : LE α] [inst_1 : LT α] [inst_2 : Std.PRange.Least? α]
  [inst_3 : Std.PRange.UpwardEnumerable α] [Std.PRange.LawfulUpwardEnumerable α] [Std.PRange.LawfulUpwardEnumerableLE α]
  [inst_6 : Std.PRange.LawfulUpwardEnumerableLeast? α] [Std.Rxo.IsAlwaysFinite α] {a : α},
  a ∈ r ↔ a ∈ Std.PRange.UpwardEnumerable.least...r.upper