func (p Pointer) IsNull() bool {
	return allZeros(p)
}
IsNull should be used instead of making explicit comparisons with
Null.
package storage
import (
	"crypto/sha256"
	"encoding/hex"
	"errors"
	"fmt"
	"math/rand"
)
type Pointer []byte
var Null = Pointer(nil)
var ErrNotHashPointer = errors.New("not hash pointer")
func allZeros(bb []byte) bool {
	for _, b := range bb {
		if b != 0 {
			return false
		}
	}
	return true
}