      NormalFormset = modelformset_factory(User, form=CustomDeleteUserForm, can_delete=True)
      DeleteFormset = modelformset_factory(User, form=CustomDeleteUserForm, formset=BaseCustomDeleteModelFormSet)
  
      data = {
              'form-TOTAL_FORMS': '4',
              'form-INITIAL_FORMS': '0',
              'form-MAX_NUM_FORMS': '4',
              'form-0-username': 'John',
              'form-0-serial': '1',
              'form-1-username': 'Paul',
              'form-1-serial': '2',
              'form-2-username': 'George',
              'form-2-serial': '3',
              'form-3-username': 'Ringo',
              'form-3-serial': '5',
              }
  
      delete_all_ids = {
              'form-0-DELETE': '1',
              'form-1-DELETE': '1',
              'form-2-DELETE': '1',
 
</s> remove             'form-0-DELETE': '1',
            'form-1-DELETE': '1',
            'form-2-DELETE': '1',
            'form-3-DELETE': '1',
            }
 </s> add         'form-0-DELETE': '1',
        'form-1-DELETE': '1',
        'form-2-DELETE': '1',
        'form-3-DELETE': '1',
    } </s> remove                 'value': 123,
                'fn': datetime.now,
 </s> add             'value': 123,
            'fn': datetime.now, </s> remove                     'title': 'Other',
                    'author': self.writer.pk,
                    'isbn': '9876',
                    'suffix1': '0',
                    'suffix2': '0'
                })
 </s> add             'title': 'Other',
            'author': self.writer.pk,
            'isbn': '9876',
            'suffix1': '0',
            'suffix2': '0'
        }) </s> remove         self.message_user(request, _(
            'The %(name)s "%(obj)s" was deleted successfully.') % {
 </s> add         self.message_user(request,
            _('The %(name)s "%(obj)s" was deleted successfully.') % { </s> remove                 'value': 123,
                'fn': datetime.now,
 </s> add             'value': 123,
            'fn': datetime.now,
        'form-TOTAL_FORMS': '4',
        'form-INITIAL_FORMS': '0',
        'form-MAX_NUM_FORMS': '4',
        'form-0-username': 'John',
        'form-0-serial': '1',
        'form-1-username': 'Paul',
        'form-1-serial': '2',
        'form-2-username': 'George',
        'form-2-serial': '3',
        'form-3-username': 'Ringo',
        'form-3-serial': '5',
    }
      NormalFormset = modelformset_factory(User, form=CustomDeleteUserForm, can_delete=True)
      DeleteFormset = modelformset_factory(User, form=CustomDeleteUserForm, formset=BaseCustomDeleteModelFormSet)
  
      data = {
        'form-TOTAL_FORMS': '4',
        'form-INITIAL_FORMS': '0',
        'form-MAX_NUM_FORMS': '4',
        'form-0-username': 'John',
        'form-0-serial': '1',
        'form-1-username': 'Paul',
        'form-1-serial': '2',
        'form-2-username': 'George',
        'form-2-serial': '3',
        'form-3-username': 'Ringo',
        'form-3-serial': '5',
    }
        'form-TOTAL_FORMS': '4',
        'form-INITIAL_FORMS': '0',
        'form-MAX_NUM_FORMS': '4',
        'form-0-username': 'John',
        'form-0-serial': '1',
        'form-1-username': 'Paul',
        'form-1-serial': '2',
        'form-2-username': 'George',
        'form-2-serial': '3',
        'form-3-username': 'Ringo',
        'form-3-serial': '5',
    }
        'form-TOTAL_FORMS': '4',
        'form-INITIAL_FORMS': '0',
        'form-MAX_NUM_FORMS': '4',
        'form-0-username': 'John',
        'form-0-serial': '1',
        'form-1-username': 'Paul',
        'form-1-serial': '2',
        'form-2-username': 'George',
        'form-2-serial': '3',
        'form-3-username': 'Ringo',
        'form-3-serial': '5',
    }
        'form-TOTAL_FORMS': '4',
        'form-INITIAL_FORMS': '0',
        'form-MAX_NUM_FORMS': '4',
        'form-0-username': 'John',
        'form-0-serial': '1',
        'form-1-username': 'Paul',
        'form-1-serial': '2',
        'form-2-username': 'George',
        'form-2-serial': '3',
        'form-3-username': 'Ringo',
        'form-3-serial': '5',
    }
        'form-TOTAL_FORMS': '4',
        'form-INITIAL_FORMS': '0',
        'form-MAX_NUM_FORMS': '4',
        'form-0-username': 'John',
        'form-0-serial': '1',
        'form-1-username': 'Paul',
        'form-1-serial': '2',
        'form-2-username': 'George',
        'form-2-serial': '3',
        'form-3-username': 'Ringo',
        'form-3-serial': '5',
    }
        'form-TOTAL_FORMS': '4',
        'form-INITIAL_FORMS': '0',
        'form-MAX_NUM_FORMS': '4',
        'form-0-username': 'John',
        'form-0-serial': '1',
        'form-1-username': 'Paul',
        'form-1-serial': '2',
        'form-2-username': 'George',
        'form-2-serial': '3',
        'form-3-username': 'Ringo',
        'form-3-serial': '5',
    }
        'form-TOTAL_FORMS': '4',
        'form-INITIAL_FORMS': '0',
        'form-MAX_NUM_FORMS': '4',
        'form-0-username': 'John',
        'form-0-serial': '1',
        'form-1-username': 'Paul',
        'form-1-serial': '2',
        'form-2-username': 'George',
        'form-2-serial': '3',
        'form-3-username': 'Ringo',
        'form-3-serial': '5',
    }
        'form-TOTAL_FORMS': '4',
        'form-INITIAL_FORMS': '0',
        'form-MAX_NUM_FORMS': '4',
        'form-0-username': 'John',
        'form-0-serial': '1',
        'form-1-username': 'Paul',
        'form-1-serial': '2',
        'form-2-username': 'George',
        'form-2-serial': '3',
        'form-3-username': 'Ringo',
        'form-3-serial': '5',
    }
        'form-TOTAL_FORMS': '4',
        'form-INITIAL_FORMS': '0',
        'form-MAX_NUM_FORMS': '4',
        'form-0-username': 'John',
        'form-0-serial': '1',
        'form-1-username': 'Paul',
        'form-1-serial': '2',
        'form-2-username': 'George',
        'form-2-serial': '3',
        'form-3-username': 'Ringo',
        'form-3-serial': '5',
    }
        'form-TOTAL_FORMS': '4',
        'form-INITIAL_FORMS': '0',
        'form-MAX_NUM_FORMS': '4',
        'form-0-username': 'John',
        'form-0-serial': '1',
        'form-1-username': 'Paul',
        'form-1-serial': '2',
        'form-2-username': 'George',
        'form-2-serial': '3',
        'form-3-username': 'Ringo',
        'form-3-serial': '5',
    }
        'form-TOTAL_FORMS': '4',
        'form-INITIAL_FORMS': '0',
        'form-MAX_NUM_FORMS': '4',
        'form-0-username': 'John',
        'form-0-serial': '1',
        'form-1-username': 'Paul',
        'form-1-serial': '2',
        'form-2-username': 'George',
        'form-2-serial': '3',
        'form-3-username': 'Ringo',
        'form-3-serial': '5',
    }
        'form-TOTAL_FORMS': '4',
        'form-INITIAL_FORMS': '0',
        'form-MAX_NUM_FORMS': '4',
        'form-0-username': 'John',
        'form-0-serial': '1',
        'form-1-username': 'Paul',
        'form-1-serial': '2',
        'form-2-username': 'George',
        'form-2-serial': '3',
        'form-3-username': 'Ringo',
        'form-3-serial': '5',
    }
  
      delete_all_ids = {
              'form-0-DELETE': '1',
              'form-1-DELETE': '1',
              'form-2-DELETE': '1',
keep keep keep keep replace replace replace replace replace replace replace replace replace replace replace replace keep keep keep keep keep
 Fixed #21288 -- Fixed E126 pep8 warnings 
tests/model_formsets_regress/tests.py