def METHOD_NAME(error: grpc.aio.AioRpcError) -> Optional[str]:
    """Return formatted string of the trailing metadata if exists otherwise return None
    :param error: AioRpcError
    :return: string of Metadata or None
    """
    if type(error) == grpc.aio.AioRpcError:
        trailing_metadata = error.trailing_metadata()
        if trailing_metadata and len(trailing_metadata):
            return f'trailing_metadata={trailing_metadata}'
    return None