///Simple wrapping of the map

   ///This \ref concept::ReadMap "read only map" returns the simple

   ///wrapping of the given map. Sometimes the reference maps cannot be

   ///combined with simple read maps. This map adaptor wraps the given

   ///map to simple read map.

   template<typename M> 

   class SimpleMap : public MapBase<typename M::Key, typename M::Value> {

     const M& m;

   public:

     typedef MapBase<typename M::Key, typename M::Value> Parent;

     typedef typename Parent::Key Key;

     typedef typename Parent::Value Value;

     ///Constructor

     SimpleMap(const M &_m) : m(_m) {};

     Value operator[](Key k) const {return m[k];}

   };

   ///Simple writeable wrapping of the map

   ///This \ref concept::ReadMap "read only map" returns the simple

   ///wrapping of the given map. Sometimes the reference maps cannot be

   ///combined with simple read-write maps. This map adaptor wraps the

   ///given map to simple read-write map.

   template<typename M> 

   class SimpleWriteMap : public MapBase<typename M::Key, typename M::Value> {

     M& m;

   public:

     typedef MapBase<typename M::Key, typename M::Value> Parent;

     typedef typename Parent::Key Key;

     typedef typename Parent::Value Value;

     ///Constructor

     SimpleWriteMap(M &_m) : m(_m) {};

     Value operator[](Key k) const {return m[k];}

     void set(Key k, const Value& c) { m.set(k, c); }

   };