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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def ensure_image(self):
 """ Ensure that config.image_url has been downloaded and unpacked. """

        image_folder = self.get_image_folder()
        if os.path.exists(image_folder):
            print(
                'OS image directory {} exists...not overwriting' .format(
                    image_folder))
            return

        ensure_image(
            self.config.image_name,
            self.config.image_url,
            IMAGES_ROOT,
            getattr(self.config, 'image_md5', None),
            self.get_image_folder()
        )