from langchain.embeddings.openai import OpenAIEmbeddings
from langchain.chains import RetrievalQA, RetrievalQAWithSourcesChain
from langchain.vectorstores import Chroma
from langchain.text_splitter import CharacterTextSplitter
from langchain import OpenAI
from langchain.document_loaders import DirectoryLoader
import magic
import os
import nltk
os.environ[“OPENAI_API_KEY”] = “**********************************”
loader = DirectoryLoader(‘store’, glob=‘**/*.txt’)
docs = loader.load()
char_text_splitter = CharacterTextSplitter(chunk_size=1000, chunk_overlap=0)
doc_texts = char_text_splitter.split_documents(docs)
openAI_embeddings = OpenAIEmbeddings(openai_api_key=os.environ[“OPENAI_API_KEY”])
vStore = Chroma.from_documents(doc_texts, openAI_embeddings)
model = RetrievalQA.from_chain_type(llm=OpenAI(), chain_type=“stuff”, vectorstore=vStore)
this code is not working, last line of this code is showing error , can any one please help me in this