          self.parent = None
          self.root = None
          self.partial = partial
  
          self.context = context or {}
  
          self.init_data = data
          self.init_files = files
 
</s> remove     target = models.OneToOneField(OneToOneTarget, related_name='target_source')
 </s> add     target = models.OneToOneField(OneToOneTarget, null=True, blank=True,
                                  related_name='target_source')
        self.delete = False
          self.parent = None
          self.root = None
          self.partial = partial
        self.delete = False
  
          self.context = context or {}
  
          self.init_data = data
          self.init_files = files
keep keep add keep keep keep keep keep
 Add one-to-one nested update and delete functionality 
rest_framework/serializers.py