title: sorting with two key= arguments
body: <p>I want a case-insensitive sort of a tuple of records (lists) on two fields in each record.  HowTo/Sorting tells me how to do case-insensitive (<code>key=str.lower</code>), and it tells me how to sort on two keys (<code>key=operator.itemgetter(0,1)</code>). I tried the following:</p>
  
  <pre><code>parts = [
      ('A',2,''),
      ('a',1,''),
      ('b',2,''),
      ('B',1,''),
  ]
  foo = sorted(parts, key=str.lower, key=operator.itemgetter(0,1))
  print(foo)
  </code></pre>
  
  <p>Python does not like two <code>key=</code>s in the same <code>sorted</code>.  It says: <code>SyntaxError: keyword argument repeated</code>, pointing to the second instance of <code>key=</code>.</p>
  
  <p>How can I get a case-insensitive sort, and sort on multiple fields, too?</p>