func Zero(hash []byte) bool {
	return bytes.Equal(hash, nullBytes)
}
Zero returns true if hash contains the zero hash.
package hash
import "bytes"
const (
	SizeBytes = 49  
	SizeTrits = 243
)
var (
	nullBytes = make([]byte, SizeBytes)
)
func WeightMagnitude(trits []int8) int {
	last := len(trits) - 1
	for i := last; i > 0; i-- {
		if trits[i] != 0 {
			return last - i
		}
	}
	return 0
}