def getScreen(self, width):
raise NotImplementedError<EOL>
Take the screenshot of the target device screen or target app's window

Args:
    width (:obj:`int`): expected width of the screenshot in pixels

Returns:
    2-:obj:`list` (:obj:`str`, :obj:`str`):
        - b64img: base64 encoded screen data
        - format: screen data format (png/jpg/etc.)