Transaction {
      version: 1,
      lock_time: LockTime::ZERO,
      input: (0..inputs)
        .map(|_| TxIn {
          previous_output: OutPoint::null(),
          script_sig: ScriptBuf::new(),
          sequence: Sequence::ENABLE_RBF_NO_LOCKTIME,
          witness: Witness::from_slice(&[&[0; Self::SCHNORR_SIGNATURE_SIZE]]),
        })
        .collect(),
      output: outputs
        .into_iter()
        .map(|address| TxOut {
          value: 0,
          script_pubkey: address.script_pubkey(),
        })
        .collect(),
    }
    .vsize()
  }

  fn estimate_fee(&self) -> Amount {
    self.fee_rate.fee(self.estimate_vbytes())
  }

  fn build(self) -> Result<Transaction> {
    let recipient = self.recipient.script_pubkey();
    let transaction = Transaction {
      version: 1,
      lock_time: LockTime::ZERO,
      input: self
        .inputs
        .iter()
        .map(|outpoint| TxIn {
          previous_output: *outpoint,
          script_sig: ScriptBuf::new(),
          sequence: Sequence::ENABLE_RBF_NO_LOCKTIME,