async placeAuctionBid (placeAuctionBid: PlaceAuctionBid, utxos: UTXO[] = []): Promise<string> {
    return await this.client.call(
      'placeauctionbid',
      [placeAuctionBid.vaultId, placeAuctionBid.index, placeAuctionBid.from, placeAuctionBid.amount, utxos],
      'number'