anchor.diff:  		 ==
   		 lists:reverse(Ys) ++ lists:reverse(Xs))).
   					 
  -prop_delete() ->
  -  fails(
  +delete_test() ->
  +    false = triq:check(
       ?FORALL(L,list(int()), 
   	?IMPLIES(L /= [],
   	    ?FORALL(I,elements(L), 
  
positive.code: 	    X < Y).
  
  
  
  
negative.code: inverse('/=') -> '=='.
  
  prop_binop() ->
      ?FORALL({A,B,OP}, {any(),any(),elements(['>','<','==','=:=','=/=','/='])},
  	    erlang:OP(A,B) 
  	    ==
  	    begin 
  