abstract class Task {
  static protected World   theWorld   = null;
  static protected Manager theManager = null;

  static void setWorld(World wld) {
    theWorld = wld;
  }

  static void setManager(Manager mgr) {
    theManager = mgr;
  }

  Client theClient = null;

  Task(Client cli) {
    theClient = cli;
  }

  abstract void execute(); 
}