Nested conditional compilation

Hi, is it possible to perform nested conditional compilation?


e.g. (For illustrative purposes only).

:- if(predicate_property(foo, built_in)).  % level 1 nesting

     print('system foo available').
   
     :- if(predicate_property(bar, built_in)).  %  level 2 nesting

         print('system foo and bar available').

     :- else.  %  level 2 nesting
         print('system bar not available').

     :- end.  % level 2 nesting

:- else.  % Level 1 nesting
    foo(X) : -  ...
    bar(Y):-  ...
  
     print('Using self defined foo and bar').

:- end. % Level 1 nesting


Thanks,

Steve

PS: New website looks great.  Kudos to the team who made it.