shukujitsu determines japanese holiday. Holidays are collected from https://www8.cao.go.jp/chosei/shukujitsu/syukujitsu.csv
When csv is updated, you can updated as follow command.
$ go run ./internal/gen/gen.go
Currently, we check it per week at here.
if shukujitsu.IsShukujitsu(time.Now()) {
fmt.Println("shukujitsu!")
}