Post 1 was Python variables.

Post 100 is GPT-4.

You've come from writing your first for loop to understanding transformer architectures, building neural networks from scratch, fine-tuning LLMs with LoRA, building RAG pipelines, and creating chatbots with memory.

This final post puts it all together. The OpenAI API is how most people actually ship AI products. Chat completions, function calling, streaming, vision, embeddings. Everything you need to build something real.

Let's finish strong.

What You'll Learn Here

API setup and authentication

Chat completions: the core pattern

System prompts: controlling model behavior

Function calling: giving LLMs tools

Streaming: responses that appear word by word

Vision: analyzing images with GPT-4V

Embeddings via API: fast, high quality

Token counting and cost management

Rate limits and error handling

A complete project: an AI assistant with tools

Setup

pip install openai tiktoken

Enter fullscreen mode

Exit fullscreen mode

import openai import os

# Set…