*1:See also https://sumita-m.hatenadiary.com/entry/20080506/1210014939 https://sumita-m.hatenadiary.com/entry/20100720/1279619992 https://sumita-m.hatenadiary.com/entry/2020/02/17/112012 https://sumita-m.hatenadiary.com/entry/2021/03/29/135748 https://sumita-m.hatenadiary.com/entry/2021/04/03/093559 https://sumita-m.hatenadiary.com/entry/2021/04/08/090706 https://sumita-m.hatenadiary.com/entry/2021/04/12/104024
