∀ {α : Type u} {β : α → Type v} [inst : Inhabited α] (x : Std.DTreeMap.Internal.Impl α β),
  x.minKey! =
    match x with
    | Std.DTreeMap.Internal.Impl.leaf =>
      panicWithPosWithDecl "Std.Data.DTreeMap.Internal.Queries" "Std.DTreeMap.Internal.Impl.minKey!" 413 13
        "Map is empty"
    | Std.DTreeMap.Internal.Impl.inner size k v Std.DTreeMap.Internal.Impl.leaf r => k
    | Std.DTreeMap.Internal.Impl.inner size k v (l@h:(Std.DTreeMap.Internal.Impl.inner size_1 k_1 v_1 l_1 r)) r_1 =>
      l.minKey!