title: list in loop, Nonetype errors
body: <p>Here is my Code</p>
  
  <pre><code>def printList(stringlist):
      empty = []
      if stringlist is None:
          print empty
      else:
          print stringlist
  
  def add (stringlist, string):
      string = [] if string is None else string
      if stringlist is not None:
          stringlist.insert(0, string)
      else:
          stringlist.append(1)
  </code></pre>
  
  <p>it somehow appears "AttributeError: 'NoneType' object has no attribute 'append'"</p>
  
  <p>I was originally looking for the code to be run like this:</p>
  
  <pre><code>&gt;&gt;&gt; myList = None
  &gt;&gt;&gt; printList(myList)
  []
  &gt;&gt;&gt; for word in ['laundry','homework','cooking','cleaning']:
  myList = add(myList, word)
  printList(myList)
  [laundry]
  [homework, laundry]
  [cooking, homework, laundry]
  [cleaning, cooking, homework, laundry]
  </code></pre>