def x;
def y = {1,2,3};
print(x);
print(y);
univ = [0, 10];


x = x \/ {3,4,5,6};
print (x /\ y);
print(~(y \ x));

5 in x \ {4,5,6};
x sub ~y;
size({7,8}) in y;

x \/ y == univ;