Writing a library for use in both Elixir and Erlang

So, @josevalim came around and suggested another way to do this which I like better as it is simpler:

elixirdoc = """
...
"""

erlangdoc = """
...
"""

for {module, moduledoc} <- [{Benchee, elixir_doc}, {:benchee, erlang_doc}] do
  defmodule module do
    @moduledoc moduledoc
    # all defs here without using
  end
end

It is implemented in this benchee PR.