title: Error when using stanford tagger in python
body: <p>This is my code and the error message:</p>
  
  <pre><code>&gt;&gt;&gt; from nltk.tag.stanford import StanfordTagger
  &gt;&gt;&gt; st = StanfordTagger('bidirection-distsim-wsj-0-18.tagger')
  
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/nltk/tag/stanford.py", line 42, in __init__
      verbose=verbose)
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/nltk/internals.py", line 597, in find_jar
      raise LookupError('\n\n%s\n%s\n%s' % (div, msg, div))
  LookupError: 
  
  ===========================================================================
    NLTK was unable to find ! Set the CLASSPATH environment variable.
  
    For more information, on , see:
      &lt;http://nlp.stanford.edu/software&gt;
  ===========================================================================
  </code></pre>
  
  <p>How can I fix that? I really want to use stanford tagger in Python
  Thank you!</p>