old_contents: from django.db import models
  
  TALK_STATUS_CHOICES = (
      ('S', 'Submitted'),
      ('A', 'Approved'),
      ('R', 'Rejected'),
      ('C', 'Confirmed'),
  )
  
  
  class Talk(models.Model):
      speaker_name = models.CharField(max_length=1000)
      speaker_email = models.CharField(max_length=1000)
      title = models.CharField(max_length=1000)
      description = models.TextField()
      sessions_available = models.ManyToManyField(
          'Session', related_name='talks_available')
      status = models.CharField(
          max_length=1, choices=TALK_STATUS_CHOICES,
          default='S')
  
      def get_absolute_url(self):
          return f'/talks/talks/{self.id}/'
  
      def __str__(self):
          return self.speaker_name
  
  
  class Session(models.Model):
      date = models.DateField()
      description = models.TextField(
          blank=True, help_text='Any special theme or info about the session.')
  
      def __str__(self):
  
          return '{} - {} '.format(self.date, self.description)
  
      def approved_talks(self):
          sets = [
              self.talks_available.filter(status=status) for status in ('A', 'C')
          ]
          return sets[0].union(sets[1])
  
      def get_absolute_url(self):
          return f'/talks/sessions/{self.id}/'
  
new_contents: from django.db import models
  from django.urls import reverse
  
  TALK_STATUS_CHOICES = (
      ('S', 'Submitted'),
      ('A', 'Approved'),
      ('R', 'Rejected'),
      ('C', 'Confirmed'),
  )
  
  
  class Talk(models.Model):
      speaker_name = models.CharField(max_length=1000)
      speaker_email = models.CharField(max_length=1000)
      title = models.CharField(max_length=1000)
      description = models.TextField()
      sessions_available = models.ManyToManyField(
          'Session', related_name='talks_available')
      status = models.CharField(
          max_length=1, choices=TALK_STATUS_CHOICES,
          default='S')
  
      def get_absolute_url(self):
          return reverse('talks-talks-id', args=[self.id])
  
      def __str__(self):
          return self.speaker_name
  
  
  class Session(models.Model):
      date = models.DateField()
      description = models.TextField(
          blank=True, help_text='Any special theme or info about the session.')
  
      def __str__(self):
  
          return '{} - {} '.format(self.date, self.description)
  
      def approved_talks(self):
          sets = [
              self.talks_available.filter(status=status) for status in ('A', 'C')
          ]
          return sets[0].union(sets[1])
  
      def get_absolute_url(self):
          return reverse('talks-sessions-id', args=[self.id])
  
subject: Use reverse to implement get_absolute_url.