title: Difference between io.FileIO and open() in binary mode
body: <p>They produce the same result based on checksum:</p>
  
  <pre><code>with open('openb', 'wb') as f:
      f.write(b'asdf')
  
  with io.FileIO('fileio', 'w') as f:
      f.write(b'asdf')
  </code></pre>
  
  <p>Is there any difference between them? When should one method be used instead of the other?</p>