Get a tarball of an image. Similar to the ``docker save`` command.

        Args:
            chunk_size (int): The generator will return up to that much data
                per iteration, but may return less. If ``None``, data will be
                streamed as it is received. Default: 2 MB
            named (str or bool): If ``False`` (default), the tarball will not
                retain repository and tag information for this image. If set
                to ``True``, the first tag in the :py:attr:`~tags` list will
                be used to identify the image. Alternatively, any element of
                the :py:attr:`~tags` list can be used as an argument to use
                that specific tag as the saved identifier.

        Returns:
            (generator): A stream of raw archive data.

        Raises:
            :py:class:`docker.errors.APIError`
                If the server returns an error.

        Example:

            >>> image = cli.get_image("busybox:latest")
            >>> f = open('/tmp/busybox-latest.tar', 'wb')
            >>> for chunk in image:
            >>>   f.write(chunk)
            >>> f.close()

def save(self, chunk_size=DEFAULT_DATA_CHUNK_SIZE, named=False):
        """
        Get a tarball of an image. Similar to the ``docker save`` command.

        Args:
            chunk_size (int): The generator will return up to that much data
                per iteration, but may return less. If ``None``, data will be
                streamed as it is received. Default: 2 MB
            named (str or bool): If ``False`` (default), the tarball will not
                retain repository and tag information for this image. If set
                to ``True``, the first tag in the :py:attr:`~tags` list will
                be used to identify the image. Alternatively, any element of
                the :py:attr:`~tags` list can be used as an argument to use
                that specific tag as the saved identifier.

        Returns:
            (generator): A stream of raw archive data.

        Raises:
            :py:class:`docker.errors.APIError`
                If the server returns an error.

        Example:

            >>> image = cli.get_image("busybox:latest")
            >>> f = open('/tmp/busybox-latest.tar', 'wb')
            >>> for chunk in image:
            >>>   f.write(chunk)
            >>> f.close()
        """
        img = self.id
        if named:
            img = self.tags[0] if self.tags else img
            if isinstance(named, six.string_types):
                if named not in self.tags:
                    raise InvalidArgument(
                        "{} is not a valid tag for this image".format(named)
                    )
                img = named

        return self.client.api.get_image(img, chunk_size)