package main
import (
	"fmt"
	"regexp"
	"time"
)
 
func main(){
	a := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
	var b []int
	windowSize := 2
 
	for i, e := 0, true; e; i++ {
		if windowSize < len(a) - windowSize * i {
			b = a[windowSize * i:windowSize * (i + 1)]
		} else {
			b = a[windowSize * i:]
			e = false
		}
 
		fmt.Println("b:", b)
	}
 
 
	usageYearMonthFormat := regexp.MustCompile(`^(\d{4})-(0[1-9]|1[012])$`)
	fmt.Println(usageYearMonthFormat.FindStringSubmatch("2025-0a"))
 
 
	jst := time.FixedZone("Asia/Tokyo", 9*60*60)
 
	fmt.Println(time.Date(2261, time.December, 30, 23, 59, 59, 0, time.UTC).UnixNano())
 
 
    fmt.Println("Format RFC3339Nano", time.Unix(0, 2057517719900000000).In(jst).Format(time.RFC3339Nano))
 
    rfcTestTime, err := time.Parse(time.RFC3339Nano, "2022-09-19T17:10:33.403859986+09:00")
    fmt.Println("Parse RFC3339Nano 2022-09-19T17:10:33.403859986+09:00: ", rfcTestTime.UnixNano(), err)
 
    rfcTestTimeEmpty, err := time.Parse(time.RFC3339Nano, "")
    fmt.Println("Parse RFC3339Nano empty: ", rfcTestTimeEmpty, err)
 
	fmt.Println("now", time.Now().UnixNano())
	fmt.Println("2261", time.Date(2261, time.December, 31, 23, 59, 59, 0, time.UTC).UnixNano())
	fmt.Println("aaaa", time.Unix(0, 9214646399000000000).In(jst))
 
	t, _ := time.Parse("2006-01-02", "2022-04-01")
	fmt.Println(t.In(jst))
	fmt.Println("startDate 2024/11/01", time.Date(2024, time.Month(11), 1, 0, 0, 0, 0, jst).UnixNano())
	fmt.Println("endDate 2023/08/24", time.Date(2023, time.Month(8), 24, 23, 59, 59, 999999999, jst).UnixNano())
	fmt.Println("endDate 2023/09/15(ms)", time.Date(2023, time.Month(9), 15, 23, 59, 59, 990000000, jst).UnixNano())
 
	startOfApril := time.Date(2022, time.Month(4), 1, 0, 0, 0, 0, jst)
	endOfApril := time.Date(2022, time.Month(4), 30, 23, 59, 59, 999999999, jst)
 
	fmt.Println("4/1", startOfApril)	
	fmt.Println("4/30", endOfApril)
	fmt.Println(endOfApril.Day() - startOfApril.Day() + 1)
 
	closingDate := time.Date(2022, time.Month(4), 20, 23, 59, 59, 999999999, jst)
 
	fmt.Println(closingDate.AddDate(0, 0, -(31 - 1)))
 
	fmt.Println(0 / 31)
}

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