import getpass import os if not os.environ.get("GOOGLE_API_KEY"): os.environ["GOOGLE_API_KEY"] = getpass.getpass("Enter API key for Google Gemini: ") from langchain.chat_models import init_chat_model model = init_chat_model("gemini-2.5-flash", model_provider="google_genai") r = model.invoke("Hello, world!") print(r)