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❓ Question

How does updating an object work?

📎 Additional context

I managed to get Mongomantic working and I can get objects from the database and also save new objects to the database. But how does updating and deleting work?
if i do this:

u= UserRepository.get(username="aaa")
u.username = str(random.randint(0,10000))
UserRepository.save(u)

I'd expect it to update the existing user in the database, but this generates a new document with the new values.

As there doesn't seem to be any documentation on updating and deleting for now: What am I doing wrong here? How does updating and deleting work?