title: python argument with or without value, specified or not
body: <p>Scenario is as follows:</p>
  
  <p>I need to implement a command line argument system that allows both</p>
  
  <p><code>-p &lt;value&gt;</code></p>
  
  <p>and</p>
  
  <p><code>-p</code></p>
  
  <p>(no value for -p given)</p>
  
  <p>Is there any way to achieve this using argparse, or will I have to manually parse sys.argv?</p>
  
  <p>Thank u so much!!!</p>