I agree with you that the current sentence:

"We have seen that the for statement is such an iterator"

is wrong. But also the new sentence IMHO is confusing, because it stills compare statementes with objects:

"the for statement expects an object that is iterable. The function list is another; it creates lists from iterables". 

Also list is a class, not a function.
IMHO the goal of the sentence you want to patch is to complete the previous one [1], adding an example of "construct" that operates with iterables, and of function that takes an iterable. If you want to follow that purpose, I suggest somethink like this:

"We have seen that the for statement is such a construct, while examples of functions that take an iterable are ``sum()`` and ``max()``::"

Written in better English than mine...


[1] "We say such an object is iterable, that is, suitable as a target for functions and constructs that expect something from which they can obtain successive items until the supply is exhausted."