) -> Result<String, jsonrpc_core::Error> {
    assert_eq!(locktime, None, "locktime param not supported");
    assert_eq!(replaceable, None, "replaceable param not supported");

    let tx = Transaction {
      version: 0,
      lock_time: LockTime::ZERO,
      input: utxos
        .iter()
        .map(|input| TxIn {
          previous_output: OutPoint::new(input.txid, input.vout),
          script_sig: ScriptBuf::new(),
          sequence: Sequence::MAX,
          witness: Witness::new(),
        })
        .collect(),
      output: outs
        .values()
        .map(|amount| TxOut {
          value: (*amount * COIN_VALUE as f64) as u64,
          script_pubkey: ScriptBuf::new(),
        })
        .collect(),
    };

    Ok(hex::encode(serialize(&tx)))
  }

  fn create_wallet(
    &self,
    name: String,
    _disable_private_keys: Option<bool>,
    _blank: Option<bool>,
    _passphrase: Option<String>,
    _avoid_reuse: Option<bool>,
  ) -> Result<LoadWalletResult, jsonrpc_core::Error> {
    self.state().wallets.insert(name.clone());