title: argument parsing in python2.7
body: <pre><code>import argparse
  
  parser = argparse.ArgumentParser(description='Process some integers.')
  parser.add_argument('-r', action='store',dest='box',type=int,help='store')
  print parser.parse_args()
  </code></pre>
  
  <p>when i try to run the above code o/p is</p>
  
  <blockquote>
    <p>>
    Namespace(box=None)</p>
  </blockquote>
  
  <p>when i give the "-r" the error rises.</p>
  
  <blockquote>
    <blockquote>
      <p>-r
      Traceback (most recent call last):
        File "", line 1, in 
          -r
      NameError: name 'r' is not defined</p>
    </blockquote>
  </blockquote>
  
  <p>how to fix this error!!!!!!!!!!!</p>