def clean(self):
                cleaned_data = super(UserImportForm, self).clean()
                users_blob = cleaned_data.get('users_blob', None)
                if users_blob:
                    users = AbstractTypeInUsersView.split_users_blob(users_blob)
                    if settings.CRADMIN_LEGACY_USE_EMAIL_AUTH_BACKEND:
                        self.__validate_users_blob_emails(emails=users)
                    else:
                        self.__validate_users_blob_usernames(usernames=users)
                    self.cleaned_users_set = users