old_contents: from django.contrib.auth.models import User
  from django.db import models
  
  
  class ConferenceOptionGroup(models.Model):
      """Used to manage relationships"""
      name = models.CharField(max_length=255)
  
      def __unicode__(self):
          return u'%s' % self.name
  
  
  class ConferenceOption(models.Model):
  
      name = models.CharField(max_length=255)
      price = models.DecimalField(max_digits=12, decimal_places=2)
      groups = models.ManyToManyField(
              ConferenceOptionGroup, related_name='members',
              help_text='Groups this option belongs to.')
      requirements = models.ManyToManyField(
              ConferenceOptionGroup, related_name='enables',
              help_text='Option groups that this relies on',
              blank=True)
  
      def __unicode__(self):
          return u'%s (%.2f)' % (self.name, self.price)
  
  
  class RegisteredAttendee(models.Model):
  
      name = models.CharField(max_length=255)
      email = models.CharField(max_length=255)
      items = models.ManyToManyField(
              ConferenceOption, related_name='attendees')
      created_by = models.ForeignKey(
              User, related_name='registeration')
  
  
  class Registration(models.Model):
      """Manages a unified registration of several attendees"""
  
      attendees = models.ManyToManyField(
              RegisteredAttendee, related_name='attendees')
      registered_by = models.ForeignKey(
              User, related_name='registeration')
  
new_contents: from django.contrib.auth.models import User
  from django.db import models
  
  
  class ConferenceOptionGroup(models.Model):
      """Used to manage relationships"""
      name = models.CharField(max_length=255)
  
      def __unicode__(self):
          return u'%s' % self.name
  
  
  class ConferenceOption(models.Model):
  
      name = models.CharField(max_length=255)
      price = models.DecimalField(max_digits=12, decimal_places=2)
      groups = models.ManyToManyField(
              ConferenceOptionGroup, related_name='members',
              help_text='Groups this option belongs to.')
      requirements = models.ManyToManyField(
              ConferenceOptionGroup, related_name='enables',
              help_text='Option groups that this relies on',
              blank=True)
  
      def __unicode__(self):
          return u'%s (%.2f)' % (self.name, self.price)
  
  
  class RegisteredAttendee(models.Model):
  
      name = models.CharField(max_length=255)
      email = models.CharField(max_length=255)
      items = models.ManyToManyField(
              ConferenceOption, related_name='attendees')
      created_by = models.ForeignKey(
              User, related_name='created')
  
  
  class Registration(models.Model):
      """Manages a unified registration of several attendees"""
  
      attendees = models.ManyToManyField(
              RegisteredAttendee, related_name='attendees')
      registered_by = models.ForeignKey(
              User, related_name='registered')
  
subject: Fix name clash