title: Python argparse - Add argument to multiple subparsers
body: <p>My script defines one main parser and multiple subparsers. I want to apply the <code>-p</code> argument to some subparsers. So far the code looks like this: </p>
  
  <pre><code>parser = argparse.ArgumentParser(prog="myProg")
  subparsers = parser.add_subparsers(title="actions")
  
  parser.add_argument("-v", "--verbose",
                      action="store_true",
                      dest="VERBOSE",
                      help="run in verbose mode")
  
  parser_create = subparsers.add_parser ("create", 
                                          help = "create the orbix environment")
  parser_create.add_argument ("-p", 
                              type = int, 
                              required = True, 
                              help = "set db parameter")
  
  # Update
  parser_update = subparsers.add_parser ("update", 
                                          help = "update the orbix environment")
  parser_update.add_argument ("-p", 
                              type = int, 
                              required = True, 
                              help = "set db parameter")
  </code></pre>
  
  <p>As you can see the <code>add_arument ("-p")</code> is repeated twice. I actually have a lot more subparsers. Is there a way to loop through the existing subparsers in order to avoid repetition?</p>
  
  <p>For the record, I am using Python 2.7</p>