code: @Test public void testNested() throws ScanException {
    List tl=new TokenStream("%(%a%(%b))").tokenize();
    List<Token> witness=new ArrayList<Token>();
    witness.add(Token.PERCENT_TOKEN);
    witness.add(Token.BARE_COMPOSITE_KEYWORD_TOKEN);
    witness.add(Token.PERCENT_TOKEN);
    witness.add(new Token(Token.SIMPLE_KEYWORD,"a"));
    witness.add(Token.PERCENT_TOKEN);
    witness.add(Token.BARE_COMPOSITE_KEYWORD_TOKEN);
    witness.add(Token.PERCENT_TOKEN);
    witness.add(new Token(Token.SIMPLE_KEYWORD,"b"));
    witness.add(Token.RIGHT_PARENTHESIS_TOKEN);
    witness.add(Token.RIGHT_PARENTHESIS_TOKEN);
    assertEquals(witness,tl);
  }
  