def content_range(self) -> ContentRange:
        """The ``Content-Range`` header as a
        :class:`~werkzeug.datastructures.ContentRange` object. Available
        even if the header is not set.

        .. versionadded:: 0.7
        """

        def on_update(rng: ContentRange) -> None:
            if not rng:
                del self.headers["content-range"]
            else:
                self.headers["Content-Range"] = rng.to_header()

        rv = parse_content_range_header(self.headers.get("content-range"), on_update)
        # always provide a content range object to make the descriptor
        # more user friendly.  It provides an unset() method that can be
        # used to remove the header quickly.
        if rv is None:
            rv = ContentRange(None, None, None, on_update=on_update)
        return rv
The ``Content-Range`` header as a
        :class:`~werkzeug.datastructures.ContentRange` object. Available
        even if the header is not set.

        .. versionadded:: 0.7
        
src/werkzeug/sansio/response.py