opEquals when your type occurs on the right hand side of an equality test

[NonNull via Digitalmars-d-learn]

I am creating a specialized bit pattern (secretly represented as 
a uint) as a struct S, but want to avoid `alias this` to maintain 
encapsulation excepting where I overtly say. Specifically, I want 
to avoid making arithmetic and inequalities available for S.

I have written opEquals to compare an S to a uint.
How do I write code to compare a uint to an S?