   ## Examples
 
       IO.warn "variable bar is unused"
-      #=> \"""
       #=> warning: variable bar is unused
-      #=>     evaluator.ex:108: IEx.Evaluator.eval/4
-      #=> \"""
+      #=>   (iex) evaluator.ex:108: IEx.Evaluator.eval/4
 
   """
   @spec warn(chardata | String.Chars.t) :: :ok

  @doc """
  Writes `item` to the given `device`, similar to `write/2`,
  but adds a newline at the end.

  """
  @spec puts(device, chardata | String.Chars.t) :: :ok
  def puts(device \\ group_leader(), item) do


      stacktrace = [{MyApp, :main, 1, [file: 'my_app.ex', line: 4]}]
      IO.warn "variable bar is unused", stacktrace
      #=> warning: variable bar is unused
      #=>   my_app.ex:4: MyApp.main/1

  """
  @spec warn(chardata | String.Chars.t, Exception.stacktrace) :: :ok
  def warn(message, []) do
