title: Python tuple instead of list
body: <p>I read some tricks about Python and met the following code. I confused that why the code create tuple with two elements in the list insted of list.
  Why python returns tuple in list instead of list in list? Is it related with are the tuples immutable?
  Thanks in advance.</p>
  
  <pre><code>&gt;&gt;&gt;import os, glob
  &gt;&gt;&gt;[(os.stat(f).st_size, os.path.realpath(f)) for f in glob.glob('*.sh')]
  [(3074, '/home/usr1/a.sh'),
  (3386, '/home/usr1/b.sh'),
  (3070, '/home/usr1/c.sh')]
  </code></pre>