I think it would be nice to have a small explanation as to why you didn’t use your unwrapped acronym above. In the end, because of the guard statement, the result is the same however we could have probably omitted that variable with a _.
As I wrote this, the idea was that you would have to unwrap acronym to get the ._rev property off of it on the same line. However, I suppose you could truncate this to one statement - I felt that being more verbose with this logic would be safer for the reader to understand.