old_contents: from django.db import models
  
  # Create your models here.
  
new_contents: from django.db import models
  from django.conf import settings
  
  
  class Conversation(models.Model):
      name = models.CharField(max_length=50)
      members = models.ManyToMany(settings.AUTH_USER_MODEL,
                                  related_name='conversations')
  
      def __str__(self):
          return self.name
  
  
  class Message(models.Model):
      text = models.TextField()
      conversation = models.ForeignKey(Conversation, related_name='messages')
      author = models.ForeignKey(settings.AUTH_USER_MODEL)
  
      def __str__(self):
          return self.text
  
subject: Add chat models