old_contents: from __future__ import unicode_literals
  
  from django.db import models
  
  # Create your models here.
  
new_contents: """
  This file represents the models for the api app.
  """
  from django.db import models
  
  
  class DateMixin(models.Model):
      """A model mixin for date creation."""
  
      created = models.DateField(auto_now_add=True)
  
  
  class File(DateMixin):
      """This class represents the file model."""
  
      name = models.CharField(max_length=100, unique=True)
      file = models.FileField(allow_files=True)
  
      def __str__(self):
          """Return a string representation of the model instance."""
          return "{}".format(self.name)
  
  
subject: define the file model