title: Does readlines() return a list or an iterator in Python 3?
body: <p>I've read in &quot;Dive into Python 3&quot; that:</p>
  <blockquote>
  <p><em>&quot;The <code>readlines()</code> method now returns an iterator, so it is just as efficient as <code>xreadlines()</code> was in Python 2&quot;.</em></p>
  </blockquote>
  <p>See: <a href="https://diveintopython3.problemsolving.io/porting-code-to-python-3-with-2to3.html#xreadlines" rel="nofollow noreferrer">Appendix A: Porting Code to Python 3 with 2to3: A.26 xreadlines() I/O method</a>.</p>
  <p>I'm not sure that's true because they don't mention it here: <a href="http://docs.python.org/release/3.0.1/whatsnew/3.0.html" rel="nofollow noreferrer">http://docs.python.org/release/3.0.1/whatsnew/3.0.html</a> . How can I check that?</p>