Does readlines() return a list or an iterator in Python 3?

I've read in "Dive into Python 3" that:

"The readlines() method now returns an iterator, so it is just as efficient as xreadlines() was in Python 2".

See: Appendix A: Porting Code to Python 3 with 2to3: A.26 xreadlines() I/O method.

I'm not sure that's true because they don't mention it here: http://docs.python.org/release/3.0.1/whatsnew/3.0.html . How can I check that?