@function __invert($map, $multi-value: false, $guard: false) {
  @if $guard and __is-iteratee-call($map, $multi-value, $guard) {
    $multi-value: null;
  }

  $props: __keys($map);
  $result: ();

  @each $key in $props {
    $value: __get($map, $key);

    @if ($multi-value) {
      @if (map-has-key($result, $value)) {
        $result: __set($result, $value, append(__get($result, $value), $key));
      } @else {
        $result: __set($result, $value, ($key));
      }
    } @else {
      $result: __set($result, $value, $key);
    }
  }

  @return $result;
}

/// Creates a map composed of the inverted keys and values of `$map`.
/// If `$map` contains duplicate values, subsequent values overwrite property
/// assignments of previous values unless `multiValue` is `true`.
///
///
/// @access public
/// @group Map
/// @param {Map} $map The map to invert.
/// @param {boolean} $multi-value [false] Allow multiple values per key.
/// @returns {Map} Returns the new inverted map.
/// @example scss
/// $map: ( 'a': 1, 'b': 2, 'c': 1 );
/// $foo: _invert($map);
/// // => ( '1': 'c', '2': 'b' )
///
/// // with `$multi-value`
/// $foo: _invert($map, true);
/// // => ( '1': ('a', 'c'), '2': ('b',) )

@function _invert($args...) {
  @return call(get-function("__invert"), $args...);
}