title: python load file content with no context manager
body: <p>I do this:</p>
  
  <pre><code>f = open('foo.txt', 'rb')
  ii = (x for x in f.readlines())
  f.close()
  
  print(next(ii))
  </code></pre>
  
  <p>I see problem in my implementation of this code with use of iterator and calling <code>next</code> after file is closed. </p>
  
  <p>Is this implementation not problematic due to a fact of using iterator and executing on iterator after the file is closed regardless of no use of context manager?</p>