Not the OP but I enjoyed the "Introduction to F#" notebook there. Interactivity let me see what the error messages are like for eaxmple replacing "negate" with "42" in the pipeline example.

(hint to Jupyter newbies: alt-enter re-evaluates the code block after editing it)

On the introduction to F# sample, there is a comment

    The best way to work with DUs is pattern matching. Using the previously-defined type definitions, we can model withdrawing money from an account:

Then a sample that has nothing to do with withdrawing money from an account.

Thanks, fixing that here: https://github.com/dotnet/try/pull/638