This is one tutorial in many programming languages. Pick your favorite, or try them all! It's the same content each time. Only the code examples change.
The code in this tutorial will always be as new as the release you are looking at. Each code snippet in the document is a piece of an actual program that was run as part of the pre-release tests.
The code snippets are extracted from those programs and placed into the documents as part of the release process.
Each page of the tutorial is small and focuses as narrowly as possible on a single topic.
At the end of each page you will have several choices about how to proceed: each choice adding a different new capability to the program you are looking at.
This allows you to choose your own course through Messenger feature-space.
So pick a language and get started!