old_contents: import uuid
  from django.db import models
  from django.utils.encoding import force_text, python_2_unicode_compatible
  
  
  @python_2_unicode_compatible
  class TestModelBase(models.Model):
      title = models.CharField(
          max_length=200,
      )
  
      content = models.TextField(
          blank=True,
      )
  
      description = models.TextField(
          blank=True,
      )
  
      is_published = models.BooleanField(
          default=True,
      )
  
      def __str__(self):
          return force_text(self.title)
  
      class Meta:
          abstract = True
  
  
  class WatsonTestModel1(TestModelBase):
  
      pass
  
  
  str_pk_gen = 0
  
  
  def get_str_pk():
      global str_pk_gen
      str_pk_gen += 1
      return str(str_pk_gen)
  
  
  class WatsonTestModel2(TestModelBase):
  
      id = models.CharField(
          primary_key=True,
          max_length=100,
          default=get_str_pk
      )
  
  
  class WatsonTestModel3(TestModelBase):
  
      id = models.UUIDField(
          primary_key=True,
          default=uuid.uuid4,
      )
  
new_contents: import uuid
  from django.db import models
  from django.utils.encoding import force_text
  
  
  class TestModelBase(models.Model):
      title = models.CharField(
          max_length=200,
      )
  
      content = models.TextField(
          blank=True,
      )
  
      description = models.TextField(
          blank=True,
      )
  
      is_published = models.BooleanField(
          default=True,
      )
  
      def __str__(self):
          return force_text(self.title)
  
      class Meta:
          abstract = True
  
  
  class WatsonTestModel1(TestModelBase):
  
      pass
  
  
  str_pk_gen = 0
  
  
  def get_str_pk():
      global str_pk_gen
      str_pk_gen += 1
      return str(str_pk_gen)
  
  
  class WatsonTestModel2(TestModelBase):
  
      id = models.CharField(
          primary_key=True,
          max_length=100,
          default=get_str_pk
      )
  
  
  class WatsonTestModel3(TestModelBase):
  
      id = models.UUIDField(
          primary_key=True,
          default=uuid.uuid4,
      )
  
subject: remove python_2_unicode_compatible from tests