title: Options with Options with Python argparse?
body: <p>I'm writing a script in Python, and using argparse to parse my arguments. The script is supposed to compare two different "aligners" from a pool of available aligners, and each aligner has some configuration options.</p>
  
  <p>I want to be able to call my script with something like:</p>
  
  <pre><code>./script.py --aligner aligner1 --param 12 --aligner aligner2 --param 30 --other_param 28
  </code></pre>
  
  <p>I want to get out of this some sort of structure where the first --param option "belongs" to the first --aligner option, and the second --param and the --other_param options "belong" to the second --aligner option.</p>
  
  <p>Is argparse capable of this sort of structured option parsing?</p>
  
  <p>If so, what is the best way to do it? If not, is there another library I should look at?</p>
  
  <p>Is there a drastically better UI design that I could be using instead of this?</p>