### Install LangChain with Google Generative AI Support

Source: https://python.langchain.com/docs/introduction/index

Installs the LangChain library with specific support for Google Generative AI. This is a prerequisite for using Google's Gemini models within LangChain.

```shell
pip install -qU "langchain[google-genai]"
```

--------------------------------

### Invoke a Chat Model in Python

Source: https://python.langchain.com/docs/introduction/index

Demonstrates how to invoke a chat model to get a response to a given input string. This is a basic example of interacting with an initialized language model.

```python
model.invoke("Hello, world!")
```

--------------------------------

### Initialize Google Gemini Chat Model in Python

Source: https://python.langchain.com/docs/introduction/index

Initializes a chat model using Google's Gemini API. It includes logic to securely retrieve the API key from environment variables or prompt the user if it's not set. Requires the 'langchain-google-genai' package.

```python
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")
```

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