*1:See also https://sumita-m.hatenadiary.com/entry/20131004/1380911282 https://sumita-m.hatenadiary.com/entry/20160908/1473302292 https://sumita-m.hatenadiary.com/entry/20160919/1474255091 https://sumita-m.hatenadiary.com/entry/2020/03/06/132427 https://sumita-m.hatenadiary.com/entry/2020/04/11/140205
