func isScriptHash(pops []parsedOpcode) bool {
	return len(pops) == 3 &&
		pops[0].opcode.value == OP_HASH160 &&
		pops[1].opcode.value == OP_DATA_20 &&
		pops[2].opcode.value == OP_EQUAL
}
isScriptHash returns true if the script passed is a pay-to-script-hash
transaction, false otherwise.
package txscript
import (
	"bytes"
	"encoding/binary"
	"fmt"
	"time"
	"github.com/btcsuite/btcd/chaincfg/chainhash"
	"github.com/btcsuite/btcd/wire"
)
var Bip16Activation = time.Unix(1333238400, 0)
type SigHashType uint32
const (
	SigHashOld          SigHashType = 0x0
	SigHashAll          SigHashType = 0x1
	SigHashNone         SigHashType = 0x2
	SigHashSingle       SigHashType = 0x3
	SigHashAnyOneCanPay SigHashType = 0x80
	sigHashMask = 0x1f
)
const (
	MaxOpsPerScript       = 201  
	MaxPubKeysPerMultiSig = 20   
	MaxScriptElementSize  = 520  
)
func isSmallInt(op *opcode) bool {
	if op.value == OP_0 || (op.value >= OP_1 && op.value <= OP_16) {
		return true
	}
	return false
}