public boolean equals(Object o) {
// Note that equals method of this class *can* be sloppy,
// since this class does not have a pattern as its child.
// Therefore datatype vocaburary does not necessarily provide
// strict equals method.
if (o.getClass() != this.getClass()) return false;
ValueExp rhs = (ValueExp) o;
if (!rhs.dt.equals(dt)) return false;
return dt.sameValue(value, rhs.value);
}
