robinrendle

@mixin sprite-bg($crop, $x:0, $y:$x, $hover:true) { 
    $i:0; 
    @each $part in $sprite { 
        @if ($part == $crop) { 
            $i:index($sprite, $part);
        } 
    }
    @if $i == 0 { 
        @warn "sprite-bg can't find '#{$crop}' in $sprite"; 
    }