*1:See also https://sumita-m.hatenadiary.com/entry/20130417/1366211836 https://sumita-m.hatenadiary.com/entry/2020/02/23/115654 https://sumita-m.hatenadiary.com/entry/2020/12/28/071837 https://sumita-m.hatenadiary.com/entry/2021/01/08/091259 https://sumita-m.hatenadiary.com/entry/2021/02/05/014636 https://sumita-m.hatenadiary.com/entry/2021/05/17/082524