def clean(self):
        cleaned_data = super(CreateCMSPageForm, self).clean()

        slug = cleaned_data.get("slug")
        sub_page = cleaned_data.get("sub_page")
        title = cleaned_data.get("title")

        if self.page:
            if sub_page:
                parent = self.page
            else:
                parent = self.page.parent
        else:
            parent = None

        if slug:
            starting_point = slug
        elif title:
            starting_point = title
        else:
            starting_point = _("page")
        slug = generate_valid_slug(starting_point, parent, self.language_code)
        if not slug:
            raise forms.ValidationError("Please provide a valid slug.")
        cleaned_data["slug"] = slug
        return cleaned_data
Look through the lists supplied by command line for the unexpected.
dataset/ETHPy150Open divio/django-cms/cms/forms/wizards.py/CreateCMSPageForm.clean--crossover with--dataset/ETHPy150Open google/gfw-toolkit/toolkit/utils/token_revoker.py/TokenRevoker.ExitIfBothBlackListsEmptys