new_contents: import pytest
  
  from flagon._compat import *
  import copy
  import traceback
  import sys
  
  def test_compat():
      assert to_bytes(None) == None
      assert to_unicode(None) == None
      with pytest.raises(ZeroDivisionError):
          try:
              s = 1/0
          except:
              exc_type, exc_value, tb = sys.exc_info()
              reraise(exc_type, exc_value, tb)
  
      with pytest.raises(ZeroDivisionError):
          try:
              s = 1/0
          except:
              exc_type, exc_value, tb = sys.exc_info()
              reraise(exc_type, exc_value, None)
  
subject: add compat testcase