Not how transformers work. How the model behaves when it is behind your API, under load, with a user typing something you did not anticipate.
For engineers integrating an LLM into a real application, who need to predict and control what comes back.
Every cost estimate, every context-window limit and every truncation bug in your application is measured in tokens, not words or characters. Getting this one unit wrong is why a feature that worked in testing bills three times what was budgeted.
Tokens: The Basic Unit of LLM Text
Using one. Nothing here trains a model. The subject is the behaviour of a model you call over an API and the engineering around it — which is what almost every production system actually needs.
The lessons are provider-neutral, because the behaviour being taught is not provider-specific. The runnable projects default to a local Ollama model so nothing costs you anything to run, and can be pointed at OpenAI or Bedrock with your own credentials.
Start with Structured Output & Validation. It is the module engineers reach for first in production, and it stands alone — though the prompting module is what stops you needing the retries.
Yes. Every project ships configured for a local model, so you can work through the track on a laptop with no API key and no per-token cost.