code: @Test public void testBasic() throws ScanException {
  {
      List tl=new TokenStream("%c").tokenize();
      List<Token> witness=new ArrayList<Token>();
      witness.add(Token.PERCENT_TOKEN);
      witness.add(new Token(Token.SIMPLE_KEYWORD,"c"));
      assertEquals(witness,tl);
    }
  {
      List tl=new TokenStream("%a%b").tokenize();
      List<Token> witness=new ArrayList<Token>();
      witness.add(Token.PERCENT_TOKEN);
      witness.add(new Token(Token.SIMPLE_KEYWORD,"a"));
      witness.add(Token.PERCENT_TOKEN);
      witness.add(new Token(Token.SIMPLE_KEYWORD,"b"));
      assertEquals(witness,tl);
    }
  {
      List tl=new TokenStream("xyz%-34c").tokenize();
      List<Token> witness=new ArrayList<Token>();
      witness.add(new Token(Token.LITERAL,"xyz"));
      witness.add(Token.PERCENT_TOKEN);
      witness.add(new Token(Token.FORMAT_MODIFIER,"-34"));
      witness.add(new Token(Token.SIMPLE_KEYWORD,"c"));
      assertEquals(witness,tl);
    }
  }
  