text: """
  Testing signals before/after saving and deleting.
  """
  from django.db import models
  
  
  class Person(models.Model):
      first_name = models.CharField(max_length=20)
      last_name = models.CharField(max_length=20)
  
      def __str__(self):
          return "%s %s" % (self.first_name, self.last_name)
  
  
  class Car(models.Model):
      make = models.CharField(max_length=20)
      model = models.CharField(max_length=20)
  
      def __str__(self):
          return "%s %s" % (self.make, self.model)
  
  
  class Author(models.Model):
      name = models.CharField(max_length=20)
  
      def __str__(self):
          return self.name
  
  
  class Book(models.Model):
      name = models.CharField(max_length=20)
      authors = models.ManyToManyField(Author)
  
      def __str__(self):
          return self.name
  