static void pointsTo(const PTSet &P)
{
	for (PTSet::const_iterator I = P.begin(), E = P.end(); I != E; ++I) {
		errs() << "\t OFF=" << I->second << " of";
		I->first->dump();
	}
}
 static nodes_iterator nodes_begin(const PTSet &G) {
   return PuntingIterator(G.begin());
 }