@app.post("/add-sources/")
async def create_file(file: UploadFile):
    print(file.filename)
    loader = SimpleDirectoryReader("")
    print("Processing PDF files...")
    source_doc = loader.load_data(file=file)
    return {"file_size": file.filename}

from llama_index.agent.openai import OpenAIAgent
from llama_index.llms.openai import OpenAI

# import and define tools
...

# initialize llm
llm = OpenAI(model="gpt-3.5-turbo-0613")

# initialize openai agent
agent = OpenAIAgent.from_tools(tools, llm=llm, verbose=True)

 100 callback_manager = callback_manager_from_settings_or_context(
    101     Settings, service_context
    102 )
    103 if len(query_engine_tools) > 0:
--> 104     callback_manager = query_engine_tools[0].query_engine.callback_manager
    106 llm = llm or llm_from_settings_or_context(Settings, service_context)
    107 if question_gen is None: