Three argument version of delta.

delta3.ex

  @spec delta(path(), any(), any()) :: delta_spec()
  defp delta(path, a, b) when is_struct(a) and is_struct(b), do: delta_struct(path, a, b)
  defp delta(path, a, b) when is_map(a) and is_map(b), do: delta_map(path, a, b)
  defp delta(path, a, b) when is_list(a) and is_list(b), do: delta_list(path, a, b)
  defp delta(path, a, b) when is_tuple(a) and is_tuple(b), do: delta_tuple(path, a, b)
  defp delta(path, a, b), do: delta_simple(path, a, b)