old_contents: # -*- coding: utf-8 -*-
  
  from django.db import models
  
  from model_utils.models import TimeStampedModel
  
  
  class BaseModel(TimeStampedModel, TitleSlugDescriptionModel):
      """
      Abstract model to store information about an experiment that may or
      may not be given.
      `title` `description`, and `slug` fields inherited from django-extensions
      TitleSlugDescriptionModel.
      """
  
      def __str__(self):
          return "{title}".format(title=self.title)
  
  
  class Experiment(BaseModel):
      pass
  
  
  class Case(BaseModel):
      pass
  
  
  class FieldGroup(BaseModel):
      pass
  
  
  class Value(TimeStampedModel):
      pass
  
  
  class Catalog(BaseModel):
      pass
  
new_contents: # -*- coding: utf-8 -*-
  
  from django.db import models
  
  from model_utils.models import TimeStampedModel, TitleSlugDescriptionModel
  
  
  class BaseModel(TimeStampedModel, TitleSlugDescriptionModel):
      """
      Abstract model to store information about an experiment that may or
      may not be given.
      `title` `description`, and `slug` fields inherited from django-extensions
      TitleSlugDescriptionModel.
      """
  
      def __str__(self):
          return "{title}".format(title=self.title)
  
  
  class Experiment(BaseModel):
      pass
  
  
  class Case(BaseModel):
      pass
  
  
  class FieldGroup(BaseModel):
      pass
  
  
  class Value(TimeStampedModel):
      pass
  
  
  class Catalog(BaseModel):
      pass
  
subject: Fix missing class