How to stop iteration with __iter__() ?

[ssecorp]

I want a parse a file of the format:
movieId
customerid, grade, date
customerid, grade, date
customerid, grade, date
etc.

so I could do with open file as reviews and then for line in reviews.

but first I want to take out the movie id so I use an iterator.

then i want to iterate through all the rows, but how can I do:
while movie_iter != None:

because that doesn't work, itraises an exception, StopItreation, which
according to the documentation it should. But catching an exception
can't be the standard way to stop iterating right?