The Readme talks about a bank account. How would transactional update look? If I want to transfer $20 from user A to user B, the following four things need to happen transactionally:

- make sure user A has the necessary funds (reserve)

- put money into user B account (debit)

- take money from user A account (credit)

- commit

At the same time, nobody else must make an operation where they see partial results, and we can't let two operations reserve the same funds in parallel.

I don't see how this use case is supported, but that may just be because I don't know where to look?