title: Python command parameter indicating time delta
body: <p>I need to specify a parameter to a python script indicating time back from now. For example <code>1d</code> is 1 day from now, <code>2h</code> is 2 hours from now, <code>2d3h</code> is 2 days, 3 hours from now. Similar to the <code>journalctl --vacuum-time</code> format (<a href="https://www.freedesktop.org/software/systemd/man/journalctl.html" rel="nofollow noreferrer">reference</a>).</p>
  <p>For example, this script will collect the data between now and 2 days and 3 hours in the past:</p>
  <pre><code>collect_data_script.py --start=2d3h
  </code></pre>
  <p>Is there some standard way to handle this parameter and a package that can process this time format? Or I will have to write it from scratch?</p>