code: func indexForHashesPerNodePrefix(addr common.Address) []byte {
  	return append([]byte{indexForNodesWithHashesPrefix}, append([]byte(addr.Hex()), keyTermByte)...)
  }
docs: // indexForHashesPerNodePrefix returns a prefix containing a node address used in
  // NodeKeys method. Node address is hex encoded to be able to use keyTermByte
  // for splitting node address and key.