code: func NewDbKey(t uint32, h common.Hash) *DBKey {
  	const sz = common.HashLength + 4
  	var k DBKey
  	k.timestamp = t
  	k.hash = h
  	k.raw = make([]byte, sz)
  	binary.BigEndian.PutUint32(k.raw, k.timestamp)
  	copy(k.raw[4:], k.hash[:])
  	return &k
  }
docs: // NewDbKey is a helper function that creates a levelDB
  // key from a hash and an integer.