use MyParser;
  $parser=new MyParser();
  $value=$parser->YYParse(yylex => \&lexer_sub, yyerror => \&error_sub);
  $nberr=$parser->YYNberr();
  $parser->YYData->{DATA}= [ 'a and ( b or c)' ];
  $data=$parser->YYData->{DATA}[0];