Single cont value
        :param elem:
        :param container_type:
        :param params:
        :param field_archiver:
        :return:

async def container_val(self, elem, container_type, params=None):
        """
        Single cont value
        :param elem:
        :param container_type:
        :param params:
        :param field_archiver:
        :return:
        """
        if hasattr(container_type, 'boost_serialize'):
            raise ValueError('not supported')

        if self.writing:
            elem_type = params[0] if params else None
            if elem_type is None:
                elem_type = container_type.ELEM_TYPE

            await self.dump_field(elem, elem_type, params[1:] if params else None)

        else:
            raise ValueError('Not supported')