BidirGraphWrapper<Graph>, the map values are different for the opposite edges.
    11 	template <typename G, typename K, typename KIt, typename V> 
 
    12 	class VectorMap : public MapBase<G, K, KIt> {
 
    17 		VectorMap(typename MapBase<G, K, KIt>::Registry& r) : MapBase<G, K, KIt>(r) {}
 
    20 		ValueType& operator[](const K& key) {
 
    21 			int id = registry->getGraph().id(key);
 
    25 		const ValueType& operator[](const K& key) const {
 
    26 			int id = registry->getGraph().id(key);
 
    30 		const ValueType& get(const K& key) const {
 
    31 			int id = registry->getGraph().id(key);
 
    35 		void set(const K& key, const ValueType& val) {
 
    36 			int id = registry->getGraph().id(key);
 
    40 		void add(const K& key) {
 
    41 			int id = registry->getGraph().id(key);
 
    42 			std::cerr << id << std::endl;
 
    43 			if (id >= container.size()) {
 
    44 				container.resize(id + 1);
 
    48 		void erase(const K& key) {}
 
    51 		typedef std::vector<ValueType> Container;