title: Datetime Subtraction in Python is non symmetric?
body: <p>When subtracting dates in python I'm finding that the results are not symmetric and the magnitude of difference depends on the order of subtraction</p>
  
  <p><strong>Code</strong></p>
  
  <pre><code>import sys
  from datetime import datetime, timezone, timedelta
  print(sys.version)
  
  datetime_1 = datetime.fromisoformat('2020-01-19 21:00:00').astimezone(timezone.utc)
  datetime_2 = datetime_1 + timedelta(hours=1)
  print(datetime_1)
  print(datetime_2)
  
  print(datetime_1 - datetime_2)
  print(datetime_2 - datetime_1)
  
  print((datetime_2 - datetime_1).seconds)
  print((datetime_1 - datetime_2).seconds)
  </code></pre>
  
  <p><strong>Output</strong></p>
  
  <pre><code>&gt; 3.7.2 (default, Dec 29 2018, 06:19:36)  [GCC 7.3.0]
  &gt; 2020-01-20 05:00:00+00:00 
  &gt; 2020-01-20 06:00:00+00:00
  &gt; -1 day, 23:00:00
  &gt; 1:00:00
  &gt; 3600
  &gt; 82800
  </code></pre>
  
  <p>My expectation is that the difference would be 3600 seconds, ignoring the sign, regardless of the order of subtraction. Any idea why this is not the case?</p>