let a = 4
let b = 7
let c = a * b + 1

assert 29 == c

let d = [[2, 4], [6, 8]]
assert 6 == d[1, 0]
assert [2, 4] == d[0]
assert [6, 8] == d[1]

let e = 0
let f = 1
assert [2, 4] == d[e]
assert [6, 8] == d[f]

let! g = 4
let! h = 7
let i = 3

h = h + i

assert 10 == h

let! j = [1, 2, 3]
j[0] = 12
j[1] = j[0] + 1
assert [12, 13, 3] == j

let! k = [[2, 4], [6, 8]]
k[1, 0] = 12
assert [[2, 4], [12, 8]] == k

k[1] = k[1] + [3]
assert [[2, 4], [12, 8, 3]] == k