anchor.diff:  unit Unit0
   
   rule GuardAgeCheck when
  -    $i: /input{ #Integer }
  -    $s: /input{ #String }
  +    $i: /input#Integer
  +    $s: /input#String
   then
       drools.guard( new AgeCheckUnit($i) );
       drools.guard( new AgeCheckUnit($s.length()) );
  
positive.code: unit TicketIssuerUnit;
  
  rule IssueAdultTicket when
      $p: /persons{ age >= 18 }
  then
      tickets.insert(new AdultTicket($p));
  end
  
negative.code: unit AdultUnit
  
  rule Adult when
      $p : /persons[age >= adultAge]
  then
      System.out.println($p.getName() + " is adult and greater than " + adultAge);
  end
  