public static function join($strings, $separator, $start = 0, $count = -1)
    {
        $string = '';

        $end = $count == -1 ? Collection::count($strings) : $count;

        for ($i = $start; $i < $end; $i++) {
            $string .= $strings[$i].$separator;

            if ($i == ($end - 1)) {
                $string .= $separator;
            }
        }

        return $string;
    }