2.1.100 Term expansion and operators

The expansion is realised by _:- pce_begin_class/[2,3]_. This predicate extends the definition of the Prolog primitive term_expansion/2 using asserta/2 to make sure it is in front of any other expansion. The returned term is a list, containing a directive that should be sent to PCE and a clause that realised the implementing predicate. Pce_begin_class/3 also declares a number of operators, notably :->, :<-, ::, * and ?.