∀ {α : Type u_1} {β : α → Type u_2} (size : ℕ) (k : α) (v : β k) (l' r' : Std.DTreeMap.Internal.Impl α β),
  (Std.DTreeMap.Internal.Impl.inner size k v l' r').Balanced →
    ∀ n < (Std.DTreeMap.Internal.Impl.inner size k v l' r').size,
      compare n l'.size = Ordering.gt → n - l'.size - 1 < r'.size