BOOST_STATIC_ASSERT((is_same<order_value_type, edge_descriptor>::value));
BOOST_CONCEPT_ASSERT((Convertible<order_size_type, edges_size_type>));
BOOST_STATIC_ASSERT((is_same<order_value_type, edge_descriptor>::value));
BOOST_CONCEPT_ASSERT((Convertible<order_size_type, edges_size_type>));