docs: def save_image(self, image, local_filename):
          """
          *Experimental:* Copies an image from Docker to a local tar file. For details, see
          :meth:`docker.client.Client.get_image`.
  
          :param image: Image name or id.
          :type image: unicode | str
          :param local_filename: Local file to store image into. Will be overwritten if present.
          :type local_filename: unicode | str
          """
          raw = self.get_image(image)
          with open(local_filename, 'wb+') as f:
              for buf in raw:
                  f.write(buf)