∀ {α : Type u} {r : Std.Rcc 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] {i : ℕ}, i < r.toList.length → (Std.PRange.succMany? i r.lower).isSome = true