private static String limit(int lower,int upper){
  if ((lower < 0) || (upper <= 0) || (upper < lower)) {
    throw new IllegalArgumentException();
  }
  return "{" + lower + ","+ upper+ "}";
}

private static String limit ( int lower , int upper ) { if ( ( lower < 0 ) || ( upper <= 0 ) || ( upper < lower ) ) { throw new IllegalArgumentException ( ) ; } return "{" + lower + "," + upper + "}" ; }
returns a regular expression quantifier with an upper and lower limit .
