How can I make something like this work?

interpolation.scss

$color-0: rgb(202,0,32);
$color-1: rgb(244,165,130);
$color-2: rgb(247,247,247);
$color-3: rgb(146,197,222);
$color-4: rgb(5,113,176);

@mixin choropleth($bucket) {
    .RdBu .q#{$bucket}-5 {
        $base-fill: $color-#{$bucket};
        fill: $base-fill;
        @include transition;
        @include transition-duration(0.25s);
        &:hover {
            fill: darken($base-fill, 10%);
        }
    }
}

@include choropleth("0");
@include choropleth("1");
@include choropleth("2");
@include choropleth("3");
@include choropleth("4");