const txb = new TransactionBlock();
const [coin1, coin2] = txb.splitCoins(
  txb.object(sourceCoinId),
  [txb.pure(10000), txb.pure(20000)]
);
txb.transferObjects(
  [coin1, coin2],
  txb.pure(sender)
);
const gaslessTx = await txb.build({provider: suiProvider, onlyTransactionKind: true});
const gaslessTxBase64 = btoa(
  gaslessTx.reduce((data, byte) => data + String.fromCharCode(byte), '')
);

const sessionToken = await keyService.shinami_key_createSession(SECRET);
const response = await walletService.shinami_wal_executeGaslessTransactionBlock(
  WALLET_ID,
  sessionToken,
  gaslessTxBase64,
  GAS_BUDGET
);