.mixin (9) {

border: 9 !important;

} .mixin (@a: 0) {

border: @a;
boxer: @a;

}

.class {

.mixin(1);
.mixin(2) !important;
.mixin(3);
.mixin(4) !important;
.mixin(5);
.mixin !important;
.mixin(9);

}