Antoine: That’s true.

Amaury: See my original bug description (“This is reasonable advice for writing an iterator class, but terrible advice for writing a container class…”), and my other comments.

There is nothing wrong with explaining how to write an iterator, but the explanation needs to make clear that this is _not_ how you write a container.  Currently the section opens with a misleading motivation (“By now you have probably noticed that most container objects can be looped over using a for statement”), but it does actually not explain how to write a container at all.  So I proposed some language and an example to fix that.