code: func (c *Client) LockUnspentAsync(unlock bool, ops []*wire.OutPoint) FutureLockUnspentResult {
  	outputs := make([]btcjson.TransactionInput, len(ops))
  	for i, op := range ops {
  		outputs[i] = btcjson.TransactionInput{
  			Txid: op.Hash.String(),
  			Vout: op.Index,
  		}
  	}
  	cmd := btcjson.NewLockUnspentCmd(unlock, outputs)
  	return c.sendCmd(cmd)
  }
docs: // LockUnspentAsync returns an instance of a type that can be used to get the
  // result of the RPC at some future time by invoking the Receive function on the
  // returned instance.
  //
  // See LockUnspent for the blocking version and more details.