inline friend void put(const Constrained_edge_map& em, key_type e, value_type b)
{
em.sm_.property(em.constraint,em.sm_.edge_handle(e.idx())) = b;
}
inline friend reference get(const Constrained_edge_map& em, key_type e)
{
bool b = em.sm_.property(em.constraint,em.sm_.edge_handle(e.idx()));
return b;
}