// Returns next indexed key based on passed number
// -------------------------------------------------------------------------------
// @param $index [Value] : index
// -------------------------------------------------------------------------------
// @return [Key] | NULL

@function next-index($index) { 
	@if $index != (length(map-fetch($flint, config)) - 1) {
		@each $key in nth(map-get($flint, config), $index + 1) {
			@return $key;
		}
	} @else {
		@return NULL;
	}
}