*1:See also https://sumita-m.hatenadiary.com/entry/20131201/1385861082 https://sumita-m.hatenadiary.com/entry/20160523/1463975503 https://sumita-m.hatenadiary.com/entry/20181005/1538730662 https://sumita-m.hatenadiary.com/entry/2019/01/03/235611 https://sumita-m.hatenadiary.com/entry/2020/06/13/153517