func block(records []Record) map[string][]Record {
	blocks := map[string][]Record{}
	for _, record := range records {
		blocks[record.City] = append(blocks[record.City], record)
	}
	return blocks
}

func main() {
	records := loadRecords(100)
	blocks := block(records)
	comparisons := 0
	matchCount := 0
	for _, blockRecords := range blocks {
		c, m := compare(blockRecords)
		comparisons += c
		matchCount += m
	}

	fmt.Printf("made %d comparisons and found %d matches\n", comparisons, matchCount)
}