Sure. So, my startup[1] does data processing for clients in aviation and finance. Due to security, legal, and regulatory requirements, sending our code on to a third party (e.g., OpenAI) is a no-go. Thanks to CodeLlama (the WizardCoder fine-tune), I've finally been able to get AI assistance with my code.
My fundamental programming skills are solid (30+ years programming!), but I only started using Python extensively relatively recently. I can get the language to do what I want it to do—but often not in the most "Pythonic" way. With CodeLlama, I'm able to check if I've done things in the "right" way, and I'm also able to ask questions when I'm trying to figure out how to implement something.
As mentioned above, I cannot use GPT-4 for my startup, but I have used it for personal stuff. My feel so far is that wizardcoder-python-34b is surprisingly good. I certainly haven't thought "oh, I wish I had GPT-4 instead"—at least, not yet! (I haven't used Copilot either, for the same reasons listed above.)
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[1] Shameless plug: https://www.amw.ai