public int hashCodeBase() {
Tuple subThis = new Tuple(fields.subList(0, fields.size() - 1));
return subThis.hashCode();
}
public int compareToBase(Tuple other) {
Tuple subThis = new Tuple(fields.subList(0, fields.size() - 1));
Tuple subThat = new Tuple(other.fields.subList(0, other.fields.size() - 1));
return subThis.compareTo(subThat);
}