cond = True
s = if cond:
    do "then block"
    do "else block"
assert s == "then block"

# else: binary operator
x = cond.then 1 else 2
assert x == 1

if! cond:
    do!:
        print! "then block"
    do!:
        print! "else block"

a = [1, 2, 3]
sum = match a:
    [x, y, z] -> x + y + z
    (x, y, z) -> x + y + z
    {x; y; z} -> x + y + z
    i: Int -> i
    _ -> panic "unknown object"

for! 0.., i =>
    print! "i = {i}"
    if i >= 100:
        do return break()

counter = !100
while! not counter.is_zero(), do!:
    print! "counter = {counter}"
    counter.dec!()