Creating a reference counted type?

[Gary Willoughby via Digitalmars-d-learn]

On Sunday, 12 June 2016 at 14:29:19 UTC, Gary Willoughby wrote:
> Another thing that is puzzling me is that when creating an 
> instance of the above struct and passing as an argument to a 
> function, the copy constructor is called and the reference 
> count is incremented. This is expected. However, when the 
> function returns, the destructor is called (on the copy) and 
> the reference count lowered. How does the original instance 
> know of the updated reference count from the copy?

Actually, this doesn't puzzle me at all! I think I must be tired. 
Ignore this paragraph, it doesn't make sense. lol.