def _CONTENT(self, fragment: Fragment) -> None:
        content = self._assume_text(fragment)
        self._fragments.append(content)

        header_json, metadata_json, content_json = [self._assume_text(x) for x in self._fragments[:3]]

        self._partial = self._protocol.assemble(header_json, metadata_json, content_json)

        self._check_complete()