func NewPrefixDB(db DB, prefix []byte) *PrefixDB {
	return &PrefixDB{
		prefix: prefix,
		db:     db,
	}
}
NewPrefixDB lets you namespace multiple DBs within a single DB.
package db
import (
	"fmt"
	"sync"
)
type PrefixDB struct {
	mtx    sync.Mutex
	prefix []byte
	db     DB
}
var _ DB = (*PrefixDB)(nil)