public void check() {
      if (myList.get(myFirst) == null) {
        throw new IllegalStateException(this + ": EqClass " + myFirst + " is missing");
      }
      if (myList.get(mySecond) == null) {
        throw new IllegalStateException(this + ": EqClass " + mySecond + " is missing");
      }
    }
public void check()