Exercise 19 needs constant update to not fail in following exercises

[mkadirtan]

Exerise 19 uses timestamp in user_data_64 field, which varies for each test run and the client throws error due to using same id with different user_data_64.

[mkadirtan]

I've just completed all the exercises, and I am writing this comment as fresh feedback on them. The concepts are explained very clearly. However, after getting to around the 15th or 16th exercise, running all of the exercises' code from the beginning starts to take too much time. Instead, I started the Tigerbeetle in another shell and proceeded with the exercises manually. It was much smoother.

Also, there is a strange behavior in the Exercise 24 which could be a bug, I'm not sure.

The following command:
tb "create_transfers id=24002 pending_id=24000 flags=post_pending_transfer;" succeeds, but accounts has 0 posted credits / debits after this. In the following exercises, it says setting amount=0 posts the full amount, or you can post partial amounts, I would expect not setting the amount would also mean posting the full amount.