*1:See also https://sumita-m.hatenadiary.com/entry/20081120/1227148853 https://sumita-m.hatenadiary.com/entry/20160801/1470065891 https://sumita-m.hatenadiary.com/entry/2019/07/02/231056 https://sumita-m.hatenadiary.com/entry/2019/07/03/134254 https://sumita-m.hatenadiary.com/entry/2019/11/20/110620 https://sumita-m.hatenadiary.com/entry/2020/05/20/002147
