title: Adding BOM (unicode signature) while saving file in python
body: <p>How can I add BOM (unicode signature) while saving file in python:</p>
  
  <pre><code>file_old = open('old.txt', mode='r', encoding='utf-8')
  file_new = open('new.txt', mode='w', encoding='utf-16-le')
  file_new.write(file_old.read())
  </code></pre>
  
  <p>I need to convert file to <code>utf-16-le + BOM</code>. Now script is working great, except that there is no BOM.</p>