A Generative AI Engineer is testing a simple prompt template in LangChain using the code below but is getting an error: from langchain.chains import LLMChain from langchain_community.llms import OpenAI from langchain_core.prompts import PromptTemplate prompt_template = "Tell me a {adjective} joke" prompt = PromptTemplate( input_variables=["adjective"], template=prompt_template ) llm = LLMChain(prompt=prompt) llm.generate([{"adjective": "funny"}]) Assuming the API key was properly defined, what change does the Generative AI Engineer need to make to fix their chain?