title: Django timezone: feeling a bit confused
body: <p>So, we have 'Europe/Moscow' TZ in our settings.
  Currently this means daylight saving (this is going to change in the future, but at the moment it's UTC+03/04).</p>
  
  <p>I understand that this TZ is used when saving dates to the DB, and when extracting them.</p>
  
  <p>Now, I have to serialize the datetime object to ISO string, including the UTC offset. What is the correct way of doing this?</p>
  
  <p>The dates don't contain the TZ info (i.e. d.strftime('%z') is empty)</p>
  
  <p>I think I could convert them to UTC and serialize with +00:00, but how do I convert them to UTC if I don't know if the specific date is +03 (Moscow winter) or +04 (Moscow summer)</p>