Prolog -- implementation

  :- module('universe',[]). 
   universe.pl  
  
  
  world_hello(_Self) :-
  	write('Hello World'),nl.
  
  world_ask(_Self, X) :-
  	write(asking(X)), nl.
  
  world_tell(_Self,Y) :-
  	Y = 'logically, ok',
  	write(telling(Y)),nl.
  
  world_halt(_Self) :-
  	halt.