*1:See also https://sumita-m.hatenadiary.com/entry/20060829/1156854296 https://sumita-m.hatenadiary.com/entry/20140618/1403024445 https://sumita-m.hatenadiary.com/entry/20160406/1459870653 https://sumita-m.hatenadiary.com/entry/2019/01/15/135754 https://sumita-m.hatenadiary.com/entry/2019/11/24/083229 https://sumita-m.hatenadiary.com/entry/2019/11/26/012021
