more rex usage examples
(previous session continued)
rex >
length(x);
9
rex >
reverse(x);
[4, 6, 5, 7, 8, 2, 1, 9, 3]
rex >
append(x, x);
[3, 9, 1, 2, 8, 7, 5, 6, 4,
3, 9, 1, 2, 8, 7, 5, 6, 4]