∀ {α : Type u} {r : Std.Roc α} [inst : LE α] [inst_1 : DecidableLE α] [inst_2 : Std.PRange.UpwardEnumerable α]
  [inst_3 : Std.PRange.LawfulUpwardEnumerable α] [Std.PRange.LawfulUpwardEnumerableLE α]
  [inst_5 : Std.Rxc.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 []