title: argparse choices structure of allowed values
body: <p>Using <code>argparse</code> in relation to <a href="https://stackoverflow.com/questions/14660876/python-dependencies-between-groups-using-argparse">Python dependencies between groups using argparse</a>, I have an argument part of some parser group of a parser - for example:</p>
  
  <pre><code>group_simulate.add_argument('-P',
                              help='simulate FC port down',
                              nargs=1,
                              metavar='fc_port_name',
                              dest='simulate')
  </code></pre>
  
  <p>How it's possible to use the <a href="http://docs.python.org/2/library/argparse.html#choices" rel="nofollow noreferrer">choices</a> to limit the choices to a list of parameters of the next structure:</p>
  
  <pre><code>1:m:"number between 1 and 10":p:"number between 1 and 4"
  </code></pre>
  
  <p>I have tried to use the range option but I couldn't find a way to create a list of choices that are acceptable </p>
  
  <p>examples:
  legal parameters: </p>
  
  <pre><code>test.py -P 1:m:4:p:2
  </code></pre>
  
  <p>not legal parameters:</p>
  
  <pre><code>test.py -P 1:p:2
  test.py -P abvds
  </code></pre>
  
  <p>Thank you very much for the help guys!</p>