I am studying data structures and the book "How to Think About Algorithms" by Jeff Edmonds (pages 46-47) claim that:
"Hopefully, all the elements that are in your set happen to be placed into different entries in the table. In this case one can
- determine whether or not an element is contained in the set,
- ask for an arbitrary element form the set,
- determine the number of elements in the set,
- iterate through all the elements,
- and add and delete elements
in constant time i.e independently of the number of items in the set."
when speaking about hash tables. I don't understand how it is possible to iterate through all the elements in constant time. Shouldn't it be $O(N)$ since we iterate through all of them?