convert timezone to string ...

I know that the server knows that ADT == -0400, and AST == -0300 ... is
there any way of reversing that? Basically, I want to say:

SELECT timezone_str(-0400, 'not dst');

and have it return ADT ... I've got a method of doing it right now, using
a function, but just find it looks so messy, just wondering if there is a
clean way of doing it ...

Thanks ...