      def duration(self):
          return self.end - self.start
  
  
  @python_2_unicode_compatible
  class Result(models.Model):
      experiment = models.ForeignKey(Experiment, models.CASCADE)
      result_time = models.DateTimeField()
  
      def __str__(self):
 
</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 
      def duration(self):
          return self.end - self.start
  
  

  class Result(models.Model):
      experiment = models.ForeignKey(Experiment, models.CASCADE)
      result_time = models.DateTimeField()
  
      def __str__(self):
keep keep keep keep replace keep keep keep keep keep
 Refs #23919 -- Removed python_2_unicode_compatible decorator usage 
tests/expressions/models.py