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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 _create_thumbnail(self, model_instance, thumbnail, image_name):
 """ Resizes and saves the thumbnail image """

        thumbnail = self._do_resize(thumbnail, self.thumbnail_size)
        full_image_name = self.generate_filename(model_instance, image_name)
        thumbnail_filename = _get_thumbnail_filename(full_image_name)
        thumb = self._get_simple_uploaded_file(thumbnail, thumbnail_filename)
        self.storage.save(thumbnail_filename, thumb)