update documentation

scss/core.scss

@@ -24,8 +24,13 @@
   @return $d and not is-null($d);
 }
 
-// Helper function
-// Return null rather than throwing an error if index is outside list range.
+/// nth-value Helper function
+/// <br>Return $default rather than throwing an error if index is not available in the list.
+///
+/// @param {array | list} $list - the haystack list to check
+/// @param {integer} $index - the needle index
+/// @param {any} $default [null] - the default value to fallback
+/// @return {any}
 @function nth-value($list, $index, $default: null) {
   @return if(length($list) >= $index, nth($list, $index), $default);
 }

scss/mixins/_animation.scss

@@ -261,9 +261,11 @@ $animation-play-state-modes: array-concat((paused, running), $css-default-modes)
 /// @param {string} $options.timing-function [ease] - animation timing function (easing)
 /// @param {string} $options.fill-mode [forwards] - animation fill mode
 /// @param {string} $options.play-state [initial] - animation play state
+/// @requires {function} extend
 /// @requires {function} is-defined
 /// @requires {function} is-animation-time
 /// @requires {function} is-animation-direction
+/// @requires {function} nth-value
 /// @requires {mixin} prefixer
 /// @example scss - Usage
 ///   .animated-element {

scss/mixins/_background.scss

@@ -38,6 +38,7 @@ $background-position-vertical-modes: array-concat((top, center, bottom), $css-de
 /// @access public
 /// @param {string | array} $bp - the background position value/values
 /// @link https://www.w3schools.com/cssref/pr_background-position.asp W3Schools background-position docs
+/// @requires {function} nth-value
 /// @return {boolean}
 @function is-background-position($bp) {
   @if is-defined($bp) {
@@ -68,6 +69,7 @@ $background-size-modes: array-concat((auto, cover, contain), $css-default-modes)
 /// @access public
 /// @param {string | array} $bs - the background size value/values
 /// @link https://www.w3schools.com/cssref/css3_pr_background-size.asp W3Schools background-size docs
+/// @requires {function} nth-value
 /// @return {boolean}
 @function is-background-size($bs) {
   @if is-defined($bs) {
@@ -149,8 +151,10 @@ $background-attachment-modes: array-concat((scroll, fixed, local), $css-default-
 /// @param {string} $options.clip [border-box] - background clip
 /// @param {string} $options.attachment [scroll] - background attachment
 /// @param {boolean} $shorthand [false] - specifies if shorthand selector will be used or not
+/// @requires {function} extend
 /// @requires {function} is-defined
 /// @requires {function} is-background-origin-clip
+/// @requires {function} nth-value
 /// @example scss - Usage
 ///   .background-element {
 ///     @include background(null url('http://test.com/image.png') null cover no-repeat null null fixed);

scss/mixins/_border.scss

@@ -38,6 +38,7 @@ $border-styles: array-concat((none, hidden, dotted, dashed, solid, double, groov
 /// @todo manage fractions (e.g. 2em 1em 4em / 0.5em 0.2em)
 /// @requires {function} is-defined
 /// @requires {function} is-border-radius-value
+/// @requires {function} nth-value
 /// @requires {mixin} prefixer
 /// @example scss - Usage - One value
 ///   .border-radius-element {
@@ -272,9 +273,10 @@ $border-modes: array-concat((none), $css-default-modes);
 /// @param {color} $options.color [transparent] - border-color
 /// @param {size} $options.radius [null] - border-radius
 /// @link https://www.w3schools.com/cssref/pr_border.asp W3Schools border docs
-/// @requires {function} is-defined
 /// @requires {function} extend
 /// @requires {function} get
+/// @requires {function} is-defined
+/// @requires {function} nth-value
 /// @example scss - Usage
 ///   .border-element {
 ///     @include border(1px null red);

scss/mixins/_box.scss

@@ -166,6 +166,8 @@ $box-bound-size-modes: array-concat((none), $css-default-modes);
 /// @param {size | percentage} $options.min-height [null] - the min height bound
 /// @param {size | percentage} $options.max-width [null] - the max width bound
 /// @param {size | percentage} $options.max-height [null] - the max height bound
+/// @requires {function} extend
+/// @requires {function} nth-value
 /// @example scss - Usage
 ///   .bounds-element {
 ///     @include box-bounds(10% null null 610px);
@@ -265,6 +267,8 @@ $box-bound-size-modes: array-concat((none), $css-default-modes);
 /// @param {size | percentage} $options.max-width [null] - the max width bound
 /// @param {size | percentage} $options.max-height [null] - the max height bound
 /// @param {boolean} $height-fallback [true] - falls back the height value to the width value, if height is not specified (useful for square sizes)
+/// @requires {function} extend
+/// @requires {function} nth-value
 /// @example scss - Usage - height fallback
 ///   .size-element {
 ///     @include box-size(100px);
@@ -395,6 +399,8 @@ $box-bound-size-modes: array-concat((none), $css-default-modes);
 /// @param {object | map} $options - the box color options
 /// @param {color} $options.color [inherit] - the color
 /// @param {color} $options.bgcolor [inherit] - the background color
+/// @requires {function} extend
+/// @requires {function} nth-value
 /// @example scss - Usage
 ///   .color-element {
 ///     @include box-color(#ffa transparent);

scss/types/_object.scss

@@ -157,6 +157,7 @@
 /// @access public
 /// @param {object | map} $o - the object to modify in
 /// @param {object | map} $objects - the objects to merge in
+/// @requires {function} is-object
 /// @example scss - Usage
 ///   $o1: (
 ///     prop1: (