title: How to pass python command line argument?
body: <p>I am a python beginner. Trying to pass some command line arguments.
  I have used the following codes. But getting errors... transaction_file = argv[1]
  IndexError: list index out of range.</p>
  
  <pre><code>    import itertools
      import re
      from sys import argv
  
  
      print ('Computing frequent item sets.')
      transaction_file = argv[1]
      parameter_file = argv[2]
      output_file = argv[3]
  </code></pre>
  
  <p>Any help is greatly appreciated. Thanks......</p>