title: string.lower in Python 3
body: <p>I had a working python script, but something must have changed in python 3.</p>
  
  <p>For example if I wanted to convert argument 1 to lowercase:</p>
  
  <pre><code>import string
  print(string.lower(sys.argv[1]))
  </code></pre>
  
  <p>It says that <code>'module' object has no attribute 'lower'</code> - OK, I understand, <code>string</code> is a module now.</p>
  
  <p>If I remove the import, and write only <code>string.lower('FOO')</code>, it complains that <code>name 'string' is not defined</code>.</p>
  
  <p>So what's the correct way to do convert a string to lowercase?</p>