fixed what the previous fix has broken (shame on me)

@@ -360,7 +360,7 @@ def extend (module) :
                 if node_attr :
                     node_attr(state, self, attr)
                 graph.add_node(str(state), attr)
-                for succ, (trans, mode) in self.successors().items() :
+                for succ, trans, mode in self.successors() :
                     attr = dict(arrowhead="normal",
                                 label="%s\\n%s" % (trans.name, mode))
                     if edge_attr :

@@ -30,7 +30,9 @@ def check (_) :
     def bounded (self, marking, max) :
         return all(len(marking(p)) == 1 for p in marking)
     def dead (self) :
-        return not bool(self.g.successors())
+        for _ in self.g.successors() :
+            return False
+        return True
     def run (self) :
         start = last = time.time()
         for state in self.g :