∀ {α : Type u} [inst : LT α] [DecidableLT α] [inst_2 : Std.PRange.UpwardEnumerable α]
  [Std.PRange.LinearlyUpwardEnumerable α] [Std.PRange.LawfulUpwardEnumerableLT α]
  [inst_5 : Std.PRange.InfinitelyUpwardEnumerable α] [Std.Rxo.IsAlwaysFinite α] [Std.PRange.LawfulUpwardEnumerable α]
  {lo hi a : α}, (a ∈ (Std.PRange.succ lo)<...Std.PRange.succ hi) = ∃ a', a = Std.PRange.succ a' ∧ a' ∈ lo<...hi