   @doc false
   defmacro __using__(_) do
     quote do
-      import AST.Node, only: [allow_args: 1, return_self: 0, rebuild_self: 2, mutate_env: 1]
+      import AST.Node, only: [
+        allow_args: 1,
+        return_self: 0,
+        rebuild_self: 2,
+        mutate_env: 1
+      ]
+
       @behaviour AST.Node
       @after_compile AST.Node
 

  @callback decode_args(map) :: {:ok, AST.args} | {:error, term}

  @doc "Execute a node"
  @callback execute(AST.args, AST.body, Macro.Env.t) :: {:ok, AST.t} | {:ok, Macro.Env.t} | {:error, Macro.Env.t, term}

  @doc false
  defmacro __after_compile__(env, _) do

          @doc false
          def unquote(arg)() do
            unless Code.ensure_loaded?(unquote(mod)) do
              msg = "Unknown CeleryScript arg: #{unquote(arg)} (#{unquote(mod)})"
              raise CompileError,
                description: msg,
                file: __ENV__.file
            end
            unquote(mod)
          end
