runtime error

Space failed. Exit code: 1. Reason: Traceback (most recent call last): File "app.py", line 2, in <module> import paperqa File "/home/user/.local/lib/python3.8/site-packages/paperqa/__init__.py", line 1, in <module> from .docs import Answer, Docs, PromptCollection, Doc, Text File "/home/user/.local/lib/python3.8/site-packages/paperqa/docs.py", line 35, in <module> class Docs(BaseModel, arbitrary_types_allowed=True, smart_union=True): File "/home/user/.local/lib/python3.8/site-packages/paperqa/docs.py", line 43, in Docs llm: Union[str, BaseLanguageModel] = ChatOpenAI( File "/home/user/.local/lib/python3.8/site-packages/langchain/load/serializable.py", line 74, in __init__ super().__init__(**kwargs) File "pydantic/main.py", line 341, in pydantic.main.BaseModel.__init__ pydantic.error_wrappers.ValidationError: 1 validation error for ChatOpenAI __root__ Did not find openai_api_key, please add an environment variable `OPENAI_API_KEY` which contains it, or pass `openai_api_key` as a named parameter. (type=value_error)

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