   """
   def unwatch(mod, handler) do
     child_id = {__MODULE__, {mod, handler}}
+
     case Supervisor.terminate_child(@name, child_id) do
       :ok ->
-         _ = Supervisor.delete_child(@name, child_id)
+        _ = Supervisor.delete_child(@name, child_id)
         :ok
+
       {:error, _} = error ->
         error
     end

  def start_link({m, f, a}) do
    case Supervisor.start_link(__MODULE__, [], name: @name) do
      {:ok, _} = ok ->
        _ = for {mod, handler, args} <- apply(m, f, a) do
          {:ok, _} = watch(mod, handler, args)
        end
        ok
      {:error, _} = error ->
        error
    end

      {:error, :already_present} ->
        _ = Supervisor.delete_child(@name, id)
        watch(mod, handler, args)

      other ->
        other
    end
