      # column (MSSQL at least).
      id = models.IntegerField(primary_key=True)
  
  
  @python_2_unicode_compatible
  class HardbackBook(Book):
      weight = models.FloatField()
  
      def __str__(self):
          return "%s (hardback): %s" % (self.name, self.weight)
 
</s> remove @python_2_unicode_compatible
 </s> add  </s> remove @python_2_unicode_compatible
 </s> add  </s> remove @python_2_unicode_compatible
 </s> add  </s> remove @python_2_unicode_compatible
 </s> add  </s> remove @python_2_unicode_compatible
 </s> add 
      # column (MSSQL at least).
      id = models.IntegerField(primary_key=True)
  
  

  class HardbackBook(Book):
      weight = models.FloatField()
  
      def __str__(self):
          return "%s (hardback): %s" % (self.name, self.weight)
keep keep keep keep replace keep keep keep keep keep
 Refs #23919 -- Removed python_2_unicode_compatible decorator usage 
tests/aggregation_regress/models.py