checksum.go
func (t ChecksumType) ChecksumSize() int {
	switch t {
	case ChecksumTypeNone:
		return 0
	case ChecksumTypeCrc32, ChecksumTypeCrc32C:
		return crc32.Size
	case ChecksumTypeFarmhash:
		return 4
	default:
		return 0
	}
}
func (t ChecksumType) ChecksumSize() int {
	switch t {
	case ChecksumTypeNone:
		return 0
	case ChecksumTypeCrc32, ChecksumTypeCrc32C:
		return crc32.Size
	case ChecksumTypeFarmhash:
		return 4
	default:
		return 0
	}
}
// ChecksumSize returns the size in bytes of the checksum calculation