last pass of for x in iterator:

[Skaperen]

i have (a reference to) an iterator that came from some function. i need to loop through the iterator. i need to "know" (something that indicates) when the last pass of the loop is happening. my first thought is to get the value len(iterator). but not all iterators implement __len__(). so, i am looking for some other way to have a flag set to a ttue value during the last pass of the loop.