/**
* In each $list pair of $breakpoint: $value replaces all values with 'inherit'
* except for one in $index position
*
* 'inherit' value when used with 'margins' or 'paddings' mixin will not produce any output
*
* @example
*	$spacer: (xs: 10px 11px 12px 13px, md: 20px 0);
*
*	$spacer-top-only: breakpointPickCssNth($spacer, 1);
* => (xs: 10px inherit inherit inherit, md: 20px inherit inherit inherit)
*	@include margins($spacer-top-only);
*
*	$spacer-bottom-only: breakpointPickCssNth($spacer, 3);
* => (xs: inherit inherit 12px inherit, md: inherit inherit 20px inherit)
*	@include paddings($spacer-bottom-only);
*/

@function breakpointPickCssNth($list, $index, $default: inherit) {
	@each $breakpoint, $value in $list {
		$value: set-nth($default $default $default $default, $index, css-nth($value, $index));
		$list: map-merge($list, ($breakpoint: $value));
	}

	@return $list;
}

/**
* In each $list pair of $breakpoint: $value replaces all values with 'inherit'
* except for top (first) and bottom (third) properties
*
* @example
*	$spacer: (xs: 10px 11px 12px 13px, md: 20px 0);
*
*	$spacer-top-bottom: breakpoint-pick-top-bottom($spacer);
* => (xs: 10px inherit 12px inherit, md: 20px inherit 20px inherit)
*	@include margins($spacer-top-bottom);
*/

@function breakpoint-pick-top-bottom($list, $default: inherit) {
	@return breakpointMapMerge(
		breakpointPickCssNth($list, 1),
		breakpointPickCssNth($list, 3)
	);
}

/**
* In each $list pair of $breakpoint: $value replaces all values with 'inherit'
* except for right (second) and left (fourth) properties
*
* @example
*	$spacer: (xs: 10px 11px 12px 13px, md: 20px 0);
*
*	$spacer-left-right: breakpoint-pick-top-bottom($spacer);
* => (xs: inherit 11px inherit 13px, md: inherit 0 inherit 0)
*	@include margins($spacer-left-right);
*/

@function breakpoint-pick-left-right($list, $default: inherit) {
	@return breakpointMapMerge(
		breakpointPickCssNth($list, 2),
		breakpointPickCssNth($list, 4)
	);
}