  
          # Ensure we clean the attributes so that we don't eg return integer
          # pk using a string representation, as provided by the url conf kwarg.
          if hasattr(obj, 'full_clean'):
              exclude = _get_validation_exclusions(obj, pk, slug_field)
              obj.full_clean(exclude)
  
  
  class DestroyModelMixin(object):
      """
 
</s> remove def _get_validation_exclusions(obj, pk=None, slug_field=None):
 </s> add def _get_validation_exclusions(obj, pk=None, slug_field=None, lookup_field=None):
            exclude = _get_validation_exclusions(obj, pk, slug_field, self.lookup_field)
  
          # Ensure we clean the attributes so that we don't eg return integer
          # pk using a string representation, as provided by the url conf kwarg.
          if hasattr(obj, 'full_clean'):
            exclude = _get_validation_exclusions(obj, pk, slug_field, self.lookup_field)
              obj.full_clean(exclude)
  
  
  class DestroyModelMixin(object):
      """
keep keep keep keep replace keep keep keep keep keep
 introduce lookup_field and add pendingdeprecationwarnings 
rest_framework/mixins.py