private static class Namer {  private static HashMap opToNumber = new HashMap();  private static int MAX_NUMBER = -1;   static int getUniqueNumber(SIROperator op) { Integer key = new Integer(op.origHashCode()); if (opToNumber.containsKey(key)) { return ((Integer)opToNumber.get(key)).intValue(); } else {  int result = ++MAX_NUMBER; opToNumber.put(key, new Integer(result)); return result; } } }
    public void assertMutable() {	Utils.assert(!IterFactory.isFinalized(this), 		     "A mutability check failed.");    }}