∀ {α : Type u} {r : Std.Roo α} [inst : LT α] [inst_1 : DecidableLT α] [inst_2 : Std.PRange.UpwardEnumerable α]
  [inst_3 : Std.PRange.LawfulUpwardEnumerable α] [Std.PRange.LawfulUpwardEnumerableLT α]
  [inst_5 : Std.Rxo.IsAlwaysFinite α],
  r.toList =
    match Std.PRange.succ? r.lower with
    | none => []
    | some next => if next < r.upper then next :: (next<...r.upper).toList else []