{α : Type u} →
  {β : α → Type v} →
    {size : ℕ} →
      {motive : Std.DTreeMap.Internal.Impl.View α β size → Sort u_1} →
        (t : Std.DTreeMap.Internal.Impl.View α β size) →
          ((k : α) →
              (v : β k) → (tree : Std.DTreeMap.Internal.Impl.Tree α β size) → motive { k := k, v := v, tree := tree }) →
            motive t