*1:See also https://sumita-m.hatenadiary.com/entry/20130925/1380134124 https://sumita-m.hatenadiary.com/entry/20140803/1407093325 https://sumita-m.hatenadiary.com/entry/2020/04/08/150902 https://sumita-m.hatenadiary.com/entry/2021/05/04/150149 https://sumita-m.hatenadiary.com/entry/2021/05/10/215503 https://sumita-m.hatenadiary.com/entry/2021/08/24/233348