Update app.py

app.py

@@ -63,6 +63,11 @@ from langchain.memory import ConversationSummaryBufferMemory,ConversationBufferM
 
 from langchain.schema import Document
 
+
+# Cohere
+from langchain.retrievers.document_compressors import CohereRerank
+from langchain_community.llms import Cohere
+
 openai_api_key = os.environ['openai_key']
 google_api_key = os.environ['gemini_key']
 HF_key = os.environ['HF_token']
@@ -240,7 +245,7 @@ vectorstore,search_type="similarity",k=4,score_threshold=None
         search_kwargs['k'] = k
     if score_threshold is not None:
         search_kwargs['score_threshold'] = score_threshold
-
+    global retriever
     retriever = vectorstore.as_retriever(
         search_type=search_type,
         search_kwargs=search_kwargs
@@ -507,7 +512,7 @@ chain = ConversationalRetrievalChain.from_llm(
         LLM_provider="Google",api_key=google_api_key,temperature=0.1,
         model_name="gemini-pro"),
     memory=create_memory("gemini-pro"),
-    retriever = retriever_Google,  #base_retriever_HF
+    retriever = retriever,  #base_retriever_HF
     llm=instantiate_LLM(
         LLM_provider="Google",api_key=google_api_key,temperature=0.5,
         model_name="gemini-pro"),