def METHOD_NAME():
    widget = widget_output.Output()
    # Try appending a message to stdout.
    widget.append_stdout("snakes!")
    expected = (_make_stream_output("snakes!", "stdout"),)
    assert widget.outputs == expected, repr(widget.outputs)
    # Try appending a second message.
    widget.append_stdout("more snakes!")
    expected += (_make_stream_output("more snakes!", "stdout"),)
    assert widget.outputs == expected, repr(widget.outputs)