Abstract exit success/failure codes

[Adam D. Ruppe]

On Thursday, 6 December 2018 at 03:14:24 UTC, Andrew Pennebaker 
wrote:
> Most operating systems today use the convention of 0 => 
> success, non-zero => fail for exit codes, but not all.

Well, D follows and offers the C way, but there is also another: 
return void.

If you return void from main, the runtime library automatically 
handles the return value. If no exception, it returns success, if 
exception, it returns failure.