*1:See also https://sumita-m.hatenadiary.com/entry/20080717/1216316647 https://sumita-m.hatenadiary.com/entry/20150325/1427256732 https://sumita-m.hatenadiary.com/entry/20160830/1472528660 https://sumita-m.hatenadiary.com/entry/2020/01/08/095516 https://sumita-m.hatenadiary.com/entry/2020/02/25/002053 https://sumita-m.hatenadiary.com/entry/2021/02/21/103027 https://sumita-m.hatenadiary.com/entry/2021/02/22/092939
