code: @Override
      public ExamSystem fork(Option[] options) {
          try {
              ExamSystem sys = new DefaultExamSystem(combine(combinedOptions, options));
              subsystems.add(sys);
              return sys;
          }
          catch (IOException exc) {
              throw new TestContainerException(exc);
          }
      }
docs: Create a new system based on *this*. The forked System remembers the forked instances in
  order to clear resources up (if desired).