How to write custom importer?

Hi, I want to double my nlu dataset , for example: “español” => “español” & “espanol” . This should happen in import phase right? But seems like document is out of date and I get this error:

** return YAMLStoryReader.read_from_file(path_to_stories, await self.get_domain()) File “/home/awoo/workspace/ubuntu-chatbot/venv/lib/python3.8/site-packages/rasa/shared/core/training_data/story_reader/”, line 81, in read_from_file self.source_name = filename AttributeError: ‘str’ object has no attribute ‘source_name’ **