code: def save(self, form, name, composite_form, commit):
          
          if self.shall_save(form, name, composite_form):
              return composite_form.save(commit=commit)
          return None
docs: This method is called by
          :meth:`django_superform.forms.SuperModelForm.save` in order to save the
          modelform that this field takes care of and calls on the nested form's
          ``save()`` method. But only if
          :meth:`~django_superform.fields.ModelFormField.shall_save` returns
          ``True``.