I think there is a spirit to this. I.e. is it an "if" in spirit. Preconditions are not really branches. They are usually `if (bad) throw;` type of thing. They

I think there is a spirit to this. I.e. is it an "if" in spirit. Preconditions are not really branches. They are usually `if (bad) throw;` type of thing. They could be replaced with `assert(!bad);`. A branch would be a function like add_todo_or_calendaritem(is_todo: bool, ...) which would need to branch on is_todo.