動いたChatコード

import os
import openai

# APIキーの設定
openai.api_key = 'API KEY'
# GPT-3モデルの指定
model_engine = "gpt-3.5-turbo"
messages = [{"role": "system", "content": "You are a helpful assistant."}]

def gptChat(user_input):
    messages.append({"role": "user", "content": user_input})

    try:
        response = openai.ChatCompletion.create(
            model=model_engine,
            messages=messages,
        )
    except openai.error.OpenAIError as e:
        print(f"Error: {e}")
        return ""

    # GPT-3からの応答
    message_content = response['choices'][0]['message']['content']
    messages.append({"role": "assistant", "content": message_content})
    return message_content

while True:
    # ユーザーからの入力を取得
    user_input = input("You: ")
    if user_input.strip().lower() == "quit":
        break
    print("GPT-3:", gptChat(user_input))