///Returns last element of `$list`.
///@ignore Documentation: http://sassylists.com/documentation.html#sl-last
///@param {List} $list - list to retrieve last value from
///@throws Cannot find last item of empty list.
///@requires sl-is-empty
///@example
///		sl-last(a b c)
///		// c
///
///@example
///		sl-last(a)
///		// a
///@example
///		sl-last(())
///		// null
///
///@return {*}
 
@function sl-last($list) {
  @if sl-missing-dependencies(sl-is-empty) == true { @return null; }

  @if sl-is-empty($list) {
    @warn "Cannot find last item of empty list.";
    @return null;
  }

  @return nth($list, -1);
}