def get_step_files(self, step):
        wizard_files = self.data[self.step_files_key].get(step, {})

        if wizard_files and not self.file_storage:
            raise NoFileStorageConfigured(
                "You need to define 'file_storage' in your "
                "wizard view in order to handle file uploads.")

        files = {}
        for field, field_dict in six.iteritems(wizard_files):
            field_dict = field_dict.copy()
            tmp_name = field_dict.pop('tmp_name')
            if (step, field) not in self._files:
                self._files[(step, field)] = UploadedFile(
                    file=self.file_storage.open(tmp_name), **field_dict)
            files[field] = self._files[(step, field)]
        return files or None
dataset/ETHPy150Open django/django-formtools/formtools/wizard/storage/base.py/BaseStorage.get_step_files/original