Scoped Operator Overloading

[Carl]

 From http://dlang.org/attribute.html
"Private means that only members of the enclosing class can 
access the member, or members and functions in the same module as 
the enclosing class."

It appears my original code works, opApply being private. 
However, I was doing my tests with a unittest block in the same 
module. Do people commonly use a designated module for these 
types of unittests? Or does D have a way of isolating a unittest 
from the module it is declared in?