a130/_sass/bourbon/helpers/_linear-side-corner-parser.scss

// Private function for linear-gradient-parser
@function _linear-side-corner-parser($image, $first-val, $prefix, $suffix, $has-multiple-vals) {
  $val-1: str-slice($first-val, 0, $has-multiple-vals - 1 );
  $val-2: str-slice($first-val, $has-multiple-vals + 1, str-length($first-val));
  $val-3: null;
  $has-val-3: str-index($val-2, " ");

  @if $has-val-3 {
    $val-3: str-slice($val-2, $has-val-3 + 1, str-length($val-2));
    $val-2: str-slice($val-2, 0, $has-val-3 - 1);
  }

  $pos: _position-flipper($val-1) _position-flipper($val-2) _position-flipper($val-3);
  $pos: unquote($pos + "");

  // Use old spec for webkit
  @if $val-1 == "to" {
    @return (
      webkit-image: -webkit- + $prefix + $pos + $suffix,
      spec-image: $image
    );
  }

  // Bring the code up to spec
  @else {
    @return (
      webkit-image: -webkit- + $image,
      spec-image: $prefix + "to " + $pos + $suffix
    );
  }
}