*1:See also https://sumita-m.hatenadiary.com/entry/20081106/1225962862 https://sumita-m.hatenadiary.com/entry/20101206/1291659249 https://sumita-m.hatenadiary.com/entry/20150327/1427424103 https://sumita-m.hatenadiary.com/entry/20180607/1528348462 https://sumita-m.hatenadiary.com/entry/20180703/1530582124 https://sumita-m.hatenadiary.com/entry/2019/02/05/183339 https://sumita-m.hatenadiary.com/entry/2020/09/19/084305
