Example mixin for the Settify mixin's blog post on Medium.com Raw

mixin-6.scss

@if $j == 1 {
	&:nth-last-#{$selector}(-n+#{length(nth($sets, $i))}):first-#{$selector} {
		@each $property in $properties {
			#{$property}: nth(nth($sets, $i), $j);
		}
	}
}
@else {
	&:nth-last-#{$selector}(-n+#{length(nth($sets, $i))}):first-#{$selector} ~ #{nth(nth(&, 1), length(nth(&, 1)))}:nth-#{$selector}(#{$j}) {
		@each $property in $properties {
			#{$property}: nth(nth($sets, $i), $j);
		}
	}
}