Runnable examples

Runnable examples

- List prerequisites and dependencies that readers need before running the example.
- Document required environment variables. Never hard-code API keys, tokens, credentials, or other secrets.
- Keep setup instructions in the same order that readers perform them.
- Introduce code with the goal or reason for the step; do not narrate every line.
- Use realistic inputs and clearly label placeholders.
- Show expected output only when it helps readers verify success, and keep it consistent with the code.
- Keep external-service calls and other opt-in behavior clearly labeled.