@Override
public int hashCode() {
assert ((t1.hashCode() ^ t2.hashCode()) == (t2.hashCode() ^ t1.hashCode()));
return t1.hashCode() ^ t2.hashCode();
}
@Override
public int hashCode() {
assert ((t1.hashCode() ^ t2.hashCode()) == (t2.hashCode() ^ t1.hashCode()));
return t1.hashCode() ^ t2.hashCode();
}