[Sass] Mixin to provide short-hand positioning syntax

_position.scss

//
// Mixin to provide short-hand positioning syntax
//  https://gist.github.com/branneman/9248961
//
//  Usage:
//   @include position(0 false 0 20rem);
//   @include position(absolute, 0 false 0 20rem);
//
@mixin position ($position: relative, $coordinates: 0 0 0 0) {

    @if type-of($position) == list {
        $coordinates: $position;
        $position: relative;
    }

    $top:    nth($coordinates, 1);
    $right:  nth($coordinates, 2);
    $bottom: nth($coordinates, 3);
    $left:   nth($coordinates, 4);

    position: $position;

    @if $top != false {
        top: $top;
    }
    @if $right != false {
        right: $right;
    }
    @if $bottom != false {
        bottom: $bottom;
    }
    @if $left != false {
        left: $left;
    }
}