Switching to LCEL

[magedhelmy1]

- [ ] bug report -> please search issues before submitting
- [ ] feature request
- [X] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)

Dear Pamela,

Thank you for the excellent work across all your repositories. It's truly inspiring and rich in content. I was wondering if there is a plan to switch to LCEL to reduce code complexity?

Best regards,
Maged

[pamelafox]

I've added a langchain example to demonstrate the very basic Langchain usage (which has a single LCEL expression). I intentionally use the OpenAI SDK in these examples to complement my slides at https://pamelafox.github.io/my-py-talks/llms-python/ but I do like to be able to show other frameworks as well.