def _write_content_types_stream(phys_writer, parts):
        """
        Write ``[Content_Types].xml`` part to the physical package with an
        appropriate content type lookup target for each part in *parts*.
        """
        content_types_blob = serialize_part_xml(
            _ContentTypesItem.xml_for(parts)
        )
        phys_writer.write(CONTENT_TYPES_URI, content_types_blob)