Update app.py

app.py

@@ -22,6 +22,8 @@ template = """Use the following pieces of context to answer the question at the
 
 QA_CHAIN_PROMPT = PromptTemplate(input_variables = ["context", "question"], template = template)
 
+vectordb = None
+
 def invoke(openai_api_key, youtube_url, prompt):
     openai.api_key = openai_api_key
     if vectordb == None: