func IsDustAmount(amount dcrutil.Amount, scriptSize int, relayFeePerKb dcrutil.Amount) bool {
	totalSize := 8 + 2 + wire.VarIntSerializeSize(uint64(scriptSize)) +
		scriptSize + 165
	return int64(amount)*1000/(3*int64(totalSize)) < int64(relayFeePerKb)
}
IsDustAmount determines whether a transaction output value and script length would
cause the output to be considered dust.  Transactions with dust outputs are
not standard and are rejected by mempools with default policies.
package txrules
import (
	"decred.org/dcrwallet/v2/errors"
	"github.com/decred/dcrd/dcrutil/v4"
	"github.com/decred/dcrd/txscript/v4"
	"github.com/decred/dcrd/wire"
)
const DefaultRelayFeePerKb dcrutil.Amount = 1e4