Take a screenshot, also called by Mixin
        Args:
            - filename(string): file name to save

        Returns:
            PIL Image object

def _take_screenshot(self):
        """Take a screenshot, also called by Mixin
        Args:
            - filename(string): file name to save

        Returns:
            PIL Image object
        """
        raw_png = self._wda.screenshot()
        img = Image.open(BytesIO(raw_png))
        return img