decode cloudflare protected email in Elixir

my_decoder.ex

defmodule MyDecoder do
  use Bitwise
  def decode_email(encoded) do
    r =
      encoded
      |> String.slice(0..1)
      |> Integer.parse(16)
      |> elem(0)

    :lists.seq(2, String.length(encoded) - 2, 2)
    |> Enum.map(fn n ->
      encoded
      |> String.slice(n..(n + 1))
      |> Integer.parse(16)
      |> elem(0)
      |> bxor(r)
    end)
    |> List.to_string()
  end
end