title: What is the difference between 'in fp' and 'in fp.readlines()'?
body: <p>What is the difference between <code>for line in fp</code> and <code>for line in fp.readlines()</code>?</p>
  
  <p></p>
  
  <pre><code>with open(filename, 'r') as fp :
      for line in fp.readlines() :
  
  #AND
  
  with open(filename, 'r') as fp :
      for line in fp :
  </code></pre>