One file, six blanks, a working order-support agent at the end of it. Each blank offers three lines — one current, two lifted from tutorials that have aged badly. Pick wrong and the line is rejected with a reason; the blank stays empty until you get it right.
Six snippets pasted in from older tutorials, each with the symptom it produces on LangChain 1.x. Some raise, some warn, one does something worse — it works, quietly and wrongly. Choose the fix you would actually ship.