def content_length(self) -> int | None:
        """The Content-Length entity-header field indicates the size of the
        entity-body in bytes or, in the case of the HEAD method, the size of
        the entity-body that would have been sent had the request been a
        GET.
        """
        return get_content_length(
            http_content_length=self.headers.get("Content-Length"),
            http_transfer_encoding=self.headers.get("Transfer-Encoding"),
        )
The Content-Length entity-header field indicates the size of the
        entity-body in bytes or, in the case of the HEAD method, the size of
        the entity-body that would have been sent had the request been a
        GET.
        
src/werkzeug/sansio/request.py