# v1
defmodule MyApp.ThingController do
 use MyApp.Web, :controller

 plug :action

 def an_action(conn, _params) do
  text conn, "V1"
 end
end

# v2
defmodule MyApp.ThingController do
 use MyApp.Web, :controller

 plug :action

 def an_action(conn, _params) do
  text conn, "V1"
 end
end