old_contents: import uuid
  
  from django.db import models, IntegrityError
  from django.utils.text import slugify
  from django.utils import timezone
  
  
  class Referral(models.Model):
      """
      Main models for referrals app.
      """
      title = models.CharField(max_length=250)
      slug = models.CharField(unique=True, blank=True, max_length=250)
      user = models.ForeignKey('users.User', related_name='referrals')
      date_created = models.DateTimeField(auto_now_add=True, default=timezone.now())
      date_updated = models.DateTimeField(auto_now=True, default=timezone.now())
      is_active = models.BooleanField(default=True)
      clicks = models.PositiveIntegerField(default=0)
  
      def __unicode__(self):
          return self.title
  
      def save(self, *args, **kwargs):
          """
          When slug/referral_id is not given, slugfy title, make it unique and save it as slug
          """
          if not self.slug:
              # make it unique using uuid module
              self.slug = slugify("{slug}-{uid}".format(slug=self.title, uid=str(uuid.uuid4())[:4]))
          super(Referral, self).save(*args, **kwargs)
new_contents: from __future__ import unicode_literals
  import uuid
  
  from django.db import models, IntegrityError
  from django.utils.text import slugify
  from django.utils import timezone
  
  
  class Referral(models.Model):
      """
      Main models for referrals app.
      """
      title = models.CharField(max_length=250)
      slug = models.CharField(unique=True, blank=True, max_length=250)
      user = models.ForeignKey('users.User', related_name='referrals')
      date_created = models.DateTimeField(auto_now_add=True, default=timezone.now())
      date_updated = models.DateTimeField(auto_now=True, default=timezone.now())
      is_active = models.BooleanField(default=True)
      clicks = models.PositiveIntegerField(default=0)
  
      def __unicode__(self):
          return self.title
  
      def save(self, *args, **kwargs):
          """
          When slug/referral_id is not given, slugfy title, make it unique and save it as slug
          """
          if not self.slug:
              # make it unique using uuid module
              self.slug = slugify("{slug}-{uid}".format(slug=self.title,
                                                      uid=unicode(uuid.uuid4())[:4]))
          super(Referral, self).save(*args, **kwargs)
subject: make everything unicode strings