code: def get_formset_class(self, form, name):
          
          if self.formset_class is not None:
              return self.formset_class
          formset_class = inlineformset_factory(
              self.get_parent_model(form, name),
              self.get_model(form, name),
              **self.formset_factory_kwargs)
          return formset_class
docs: Either return the formset class that was provided as argument to the
          __init__ method, or build one based on the ``parent_model`` and
          ``model`` attributes.