1 + 2 * 3 = 7
(1 + 2) * 3 = 9
2 ^ 3 ^ 2 = 512
-7 / 2 = -3
-7 % 3 = -1
7 % -3 = 1
100 / (5 - 5) = error: division by zero
2 * (3 + 4 = error: missing )
10 - 4 - 3 = 3
8 / 2 / 2 = 2
2 ^ 10 - 1 = 1023
3 + = error: number expected
12 abc = error: unexpected "abc"
6 * 7 = 42
-(2 + 3) * -4 = 20
