// Testing sum

[

sum(A);
sum(A,1);
sum(A,2);

sum(A(3));
sum(A(3),1);
sum(A(3),2);

sum(A(4):=3);
sum(A(4):=a(3));
sum(A(5):=3,1);
sum(A(6):=3,2);

sum(u1);
sum(u1,1);
sum(u1,2);

sum(u1(3));
sum(u1(3),1);
sum(u1(3),2);

sum(u1(4):=3);
sum(u1(4):=a(3));
sum(u1(5):=3,1);
sum(u1(6):=3,2);

]
