title: String functions do not work with ConcatenatedCorpusView Object
body: <p>This is what I have right now:</p>
  
  <pre><code>from nltk.corpus import brown
  w = brown.words()
  print w.lower()
  </code></pre>
  
  <p>But when I run it, it says </p>
  
  <pre><code>AttributeError: 'ConcatenatedCorpusView' object has no attribute 'lower'
  </code></pre>
  
  <p>What the heck is going on and how can I fix this???</p>