.named-colors-in-expressions {
    color-0: 0 -red;  
    color-1: 1 - red; 
    color-2: red * 2;
    color-3: 2 * red;
    @3: -red;
    &-bar@{3} {x: y}
    @color: red;
    &-bar@{color} {a: a};
    background-color: blue-2;
    color: green-black;
    animation: blue-change 5s infinite;
}