Update app.py

app.py

@@ -5,15 +5,19 @@ from langchain.schema import HumanMessage, AIMessage
 from langchain.chains import create_retrieval_chain, create_history_aware_retriever
 from langchain.chains.combine_documents import create_stuff_documents_chain
 from langchain.vectorstores import Chroma
-from langchain.llms import HuggingFacePipeline
+from langchain_community.llms import HuggingFacePipeline
 from langchain.prompts import ChatPromptTemplate, MessagesPlaceholder
 from transformers import AutoTokenizer, AutoModelForCausalLM, BitsAndBytesConfig, pipeline
 
 import os
 from huggingface_hub import login
 
-# Authenticate using the token stored in the environment variable
-hf_token = os.getenv("SP_7")
+# Authenticate using your Hugging Face token stored as 'SP_7'
+hf_token = os.getenv("SP_7")  # Reads the token from the environment variable
+if hf_token is None:
+    raise ValueError("Hugging Face token 'SP_7' is not set in the environment variables.")
+
+# Log in to Hugging Face
 login(token=hf_token)