old_contents: from django.db import models
  
  
  class Timer(models.Model):
      name = models.CharField(max_length=255)
      seconds = models.PositiveIntegerField(default=0,
                                            verbose_name="Time in Seconds")
  
      def increment_time(self, seconds):
          self.seconds += seconds
  
new_contents: from django.db import models
  
  
  class Timer(models.Model):
      name = models.CharField(max_length=255)
      seconds = models.PositiveIntegerField(default=0,
                                            verbose_name="Time in Seconds")
  
subject: Update timer/models.py