text: from django.contrib.auth import models as auth
  from django.db import models
  from django.utils.encoding import python_2_unicode_compatible
  
  
  # No related name is needed here, since symmetrical relations are not
  # explicitly reversible.
  @python_2_unicode_compatible
  class SelfRefer(models.Model):
      name = models.CharField(max_length=10)
      references = models.ManyToManyField('self')
      related = models.ManyToManyField('self')
  
      def __str__(self):
          return self.name
  
  
  @python_2_unicode_compatible
  class Tag(models.Model):
      name = models.CharField(max_length=10)
  
      def __str__(self):
          return self.name
  
  
  # Regression for #11956 -- a many to many to the base class
  @python_2_unicode_compatible
  class TagCollection(Tag):
      tags = models.ManyToManyField(Tag, related_name='tag_collections')
  
      def __str__(self):
          return self.name
  
  
  # A related_name is required on one of the ManyToManyField entries here because
  # they are both addressable as reverse relations from Tag.
  @python_2_unicode_compatible
  class Entry(models.Model):
      name = models.CharField(max_length=10)
      topics = models.ManyToManyField(Tag)
      related = models.ManyToManyField(Tag, related_name="similar")
  
      def __str__(self):
          return self.name
  
  
  # Two models both inheriting from a base model with a self-referential m2m field
  class SelfReferChild(SelfRefer):
      pass
  
  
  class SelfReferChildSibling(SelfRefer):
      pass
  
  
  # Many-to-Many relation between models, where one of the PK's isn't an Autofield
  @python_2_unicode_compatible
  class Line(models.Model):
      name = models.CharField(max_length=100)
  
      def __str__(self):
          return self.name
  
  
  class Worksheet(models.Model):
      id = models.CharField(primary_key=True, max_length=100)
      lines = models.ManyToManyField(Line, blank=True)
  
  
  # Regression for #11226 -- A model with the same name that another one to
  # which it has a m2m relation. This shouldn't cause a name clash between
  # the automatically created m2m intermediary table FK field names when
  # running migrate
  class User(models.Model):
      name = models.CharField(max_length=30)
      friends = models.ManyToManyField(auth.User)
  
  
  class BadModelWithSplit(models.Model):
      name = models.CharField(max_length=1)
  
      def split(self):
          raise RuntimeError('split should not be called')
  
      class Meta:
          abstract = True
  
  
  class RegressionModelSplit(BadModelWithSplit):
      """
      Model with a split method should not cause an error in add_lazy_relation
      """
      others = models.ManyToManyField('self')
  
  
  # Regression for #24505 -- Two ManyToManyFields with the same "to" model
  # and related_name set to '+'.
  class Post(models.Model):
      primary_lines = models.ManyToManyField(Line, related_name='+')
      secondary_lines = models.ManyToManyField(Line, related_name='+')
  