*1:See also https://sumita-m.hatenadiary.com/entry/20071107/1194459675 https://sumita-m.hatenadiary.com/entry/20140730/1406693032 https://sumita-m.hatenadiary.com/entry/20161130/1480485070 https://sumita-m.hatenadiary.com/entry/20170318/1489814835 https://sumita-m.hatenadiary.com/entry/2019/09/19/095636 https://sumita-m.hatenadiary.com/entry/2021/08/13/002531 https://sumita-m.hatenadiary.com/entry/2021/09/08/094249