🚀 go-pugleaf

It's probably a bad idea to completely switch off singleton warnings.
You'll definitely have to pay a price in uncaught bugs as you keep on
with the development of your program.

I'm not sure about SICStus, but in Quintus Prolog, it's enough to
use '_' (underscore) as the first character in the variable name,
and no singleton warning will be given for that variable. Personally,
I think it's good programming style to use such variable names for
singeltons, whenever it isn't clear from the context why the singleton
can be ignored. As Ralf points out, just a '_' doesn't make the code more
readable.