Method insert

src/svgfill/src/graph_2d.h:420–424

    }

    void insert(const Point_2& u, const Point_2& v) {
        adjacency_list[u].insert(v);
        adjacency_list[v].insert(u);
        assert_symmetric();
    }

    // Iterators over vertices
    typedef typename std::map<Point_2, std::set<Point_2>>::const_iterator vertex_const_iterator;