title: word_tokenize TypeError: expected string or buffer
body: <p>When calling <code>word_tokenize</code> I get the following error:</p>
  
  <pre><code>File "C:\Python34\lib\site-packages\nltk\tokenize\punkt.py", line 1322,
      in _slices_from_text for match in
      self._lang_vars.period_context_re().finditer(text):
  TypeError: expected string or buffer
  </code></pre>
  
  <p>I have a large text file (1500.txt) from which I want to remove stop words.
  My code is as follows:</p>
  
  <pre><code>from nltk.corpus import stopwords
  from nltk.tokenize import word_tokenize
  
  with open('E:\\Book\\1500.txt', "r", encoding='ISO-8859-1') as File_1500:
      stop_words = set(stopwords.words("english"))
      words = word_tokenize(File_1500)
      filtered_sentence = [w for w in words if not w in stop_words]
      print(filtered_sentence)
  </code></pre>