 
       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
-      #=> \"""
+      #=>   my_app.ex:4: MyApp.main/1
+
   """
   @spec warn(chardata | String.Chars.t, Exception.stacktrace) :: :ok
   def warn(message, []) do

  @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

  ## Examples

      IO.warn "variable bar is unused"
      #=> warning: variable bar is unused
      #=>   (iex) evaluator.ex:108: IEx.Evaluator.eval/4

  """
  @spec warn(chardata | String.Chars.t) :: :ok
