title: How to convert a UTC datetime to a local datetime using only standard library?
body: <p>I have a python <code>datetime</code> instance that was created using <code>datetime.utcnow()</code> and persisted in database.</p>
  <p>For display, I would like to convert the <code>datetime</code> instance retrieved from the database to local <code>datetime</code> using the default local timezone (i.e., as if the <code>datetime</code> was created using <code>datetime.now()</code>).</p>
  <p>How can I convert the UTC <code>datetime</code> to a local <code>datetime</code> using only python standard library (e.g., no <code>pytz</code> dependency)?</p>
  <p>It seems one solution would be to use <code>datetime.astimezone(tz)</code>, but how would you get the default local timezone?</p>