multiple box shadows in Sass

gistfile1.sass

@mixin box-shadow ($string) {
  -webkit-box-shadow: $string;
  -moz-box-shadow:    $string;
  box-shadow:         $string;
}

.stack {
   @include box-shadow((
        1px 1px   0 rgba(0,   0,   0,   0.100),
        3px 3px   0 rgba(255, 255, 255, 1.0),
        4px 4px   0 rgba(0,   0,   0,   0.125)
   ));
}

// @include box-shadow(( whatever, you, want, just, one, param ));