// -----------------------------------------------------------------------------
// Mixin: Color variant
// -----------------------------------------------------------------------------

// Add a key/value list to generate color emphasis styles.
//
// @param {()} $list - key/value pair list.
// @param {string} $prop=color - CSS property to add value to.
// @param {boolean} $anchor=true - Create a<key>:hover selector.

@mixin _color-variant( $list, $prop: color, $anchor: true ) {
  @each $selector, $value in $list {
    .#{$selector}        { #{unquote($prop)}: $value; }

    @if $anchor {
      a.#{$selector}:hover { #{unquote($prop)}: darken($value, 10%); }
    }
  }
}

// -----------------------------------------------------------------------------
// Mixin: Color variant
// -----------------------------------------------------------------------------

// Add a key/value list to generate color emphasis styles.
//
// @param {()} $list - key/value pair list.
// @param {string} $prop=color - CSS property to add value to.
// @param {boolean} $anchor=true - Create a<key>:hover selector.

@mixin _color-variant( $list, $prop: color, $anchor: true ) {

  @each $selector, $value in $list {

    .#{$selector} {
      #{unquote($prop)}: $value;
    }

    @if $anchor {
      a.#{$selector}:hover { #{unquote($prop)}: darken($value, 10%); }
    }

  }

}

Add some line breaks to make code easier to read.
style(color-variant): Add some line breaks to make code easier to read.
