title: What's the name of argument to pass to action? (argparse)
body: <pre><code>start_check_stop = parser.add_mutually_exclusive_group()
  start_check_stop.add_argument('-s', '--start', action=start(*what*))
  start_check_stop.add_argument('-c', '--check', action=check(*what*))
  start_check_stop.add_argument('-t', '--stop', action=stop(*what*))
  </code></pre>
  
  <p>What do I need to pass in the spot labeled <em>what</em> in order to pass the given command line argument to the function?</p>