title: Adding extension to multiple files (Python3.5)
body: <p>I have a bunch of files that do not have an extension to them.</p>
  
  <pre><code>file needs to be file.txt
  </code></pre>
  
  <p>I have tried different methods (didn't try the complicated ones since I am just learning to do a bit of advanced python).</p>
  
  <p>here is one that I tried:</p>
  
  <pre><code>import os
  pth = 'B:\\etc'
  os.chdir(pth)
  for files in os.listdir('.'):
    changeName = 'files{ext}'.format(ext='.txt')
  </code></pre>
  
  <p>I tried the append, replace and rename methods as well and it didn't work for me. or those don't work in the 1st place with what I am trying to do?</p>
  
  <p>What am I missing or doing wrong?.</p>