pub fn new_service<P2P, Importer, DB>(
    config: Config,
    db: DB,
    importer: Importer,
    p2p: P2P
) -> Service<P2P, DB>where
    Importer: BlockImporter,
    P2P: PeerToPeer<GossipedTransaction = TransactionGossipData> + 'static,
    DB: TxPoolDb + 'static,