@function conds($val) {
    @if $val {
        @return "red";
    }

    @return "blue";
}

div {
    @if something {
        color: blue;
    }
}

pre {
    val-1: conds(true);
    val-2: conds(false);
    val-3: conds(null);
    val-4: conds(1);
    val-5: conds(0);
}


span {
    @if false {
        color: red;
    } @else {
        color: blue;
    }

    @if true {
        height: 10px;
    } @else {
        color: 20px;
    }

    @if false {
        height: 10px;
    } @elseif false {
        color: 20px;
    } @else {
        width: 20px;
    }
}

div {
    @if false {
        color: red;
    } @else if false {
        color: green;
    } @else {
        color: blue;
    }

    @if false {
        border-color: red;
    } @else if true {
        border-color: green;
    } @else {
        border-color: blue;
    }

}

$return: (1);
@if $return == () {
    @warn 'empty list';
}

// @if with parenthesis but no global parenthesis
$test: "1";
$test2: "2";
@if ($test == "1") and ($test2 == "2") {
  .debug {color:red;}
}