func HexDecode(str string) []byte {
	b, _ := hex.DecodeString(str)
	return b
}
func HexDecode(str string) []byte {
	b, _ := hex.DecodeString(str)
	return b
}
func HexDecode ( str string ) [ ] byte { b , _ := hex . DecodeString ( str ) return b }
// HexDecode hex decodes the str. If str is not valid hex
// it will return an empty byte slice.
HexDecode hex decodes the str . If str is not valid hex it will return an empty byte slice .