*1:See also https://sumita-m.hatenadiary.com/entry/20130607/1370563792 https://sumita-m.hatenadiary.com/entry/20140827/1409112308 https://sumita-m.hatenadiary.com/entry/20150716/1437058027 https://sumita-m hatenadiary.com/entry/20181005/1538730662 https://sumita-m.hatenadiary.com/entry/2020/06/01/145035