public int compareTo(Object o){
	Symbol s = (Symbol) o;
	if(this.equals(o))
		return 0;
	if(this.ns == null && s.ns != null)
		return -1;
	if(this.ns != null)
		{
		if(s.ns == null)
			return 1;
		int nsc = this.ns.compareTo(s.ns);
		if(nsc != 0)
			return nsc;
		}
	return this.name.compareTo(s.name);
}