You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: checksum.go
    path of file: ./repos/fq/format/postgres/common
    
    the code of the file until where you have to start completion: package common

import "encoding/binary"

const (
	nSums        = 32
	fnvPrime     = 16777619
	nSumsSize    = 4 * nSums
	mainBlockLen = PageSize /
    
func CheckSumBlock(page []byte, blockNumber uint32) uint16 {
	// set pd_checksum to zero
	page[8] = 0
	page[9] = 0

	sum := pgChecksumBlock(page)
	sum1 := sum ^ blockNumber
	sum2 := uint16((sum1 % 65535) + 1)
	return sum2
}