1<===> input.scss
2@if true {
3  div {
4    background: green;
5  }
6}
7@if not true {
8  div {
9    background: red;
10  }
11}
12@if not not true {
13  div {
14    background: blue;
15  }
16}
17@if not (true or false) {
18  div {
19    background: black;
20  }
21}
22<===> output.css
23div {
24  background: green;
25}
26
27div {
28  background: blue;
29}
30