a = 3;
b = 6;

assert(true);

assert("t1");

assert(a*b);

assert(condition = a*b);

assert(true) cube(8, center = true);

c = 2;
translate([0, 20, 0])
assert(condition = 2)
sphere(5);

d = c + 9;
assert(condition = d + 5 > 15, message = str("value: ", d + 5))
translate([15, 0, 0])
cylinder(8, 5, center = true);

echo("assert-tests");