* Aren't they a bit too much depending on the container implementation?
* What should happen when the `front` and `back` are not in the same list?
  - If implementations need to check, then it'd take O(n).

Some trivial things (not related to subject):
- 'Rationale' and 'Implementation' sections have `â€` (corruption or only me?)
- 'Copyright' has `Â` (again only me?)
Takashi Kato
Email: xxxxxx@ymail.com