def grab_image(self):
<EOL>queue = self._pebble.get_endpoint_queue(ScreenshotResponse)<EOL>self._pebble.send_packet(ScreenshotRequest())<EOL>return self._read_screenshot(queue)<EOL>
Takes a screenshot. Blocks until completion, or raises a :exc:`.ScreenshotError` on failure.

While this method is executing, "progress" events will periodically be emitted with the following signature: ::

   (downloaded_so_far, total_size)

:return: A list of bytearrays in RGB8 format, where each bytearray is one row of the image.