Method add_loop_edge

src/PLPSLAM/data/graph_node.cc:404–410

        }

        void graph_node::add_loop_edge(keyframe *keyfrm)
        {
            std::lock_guard<std::mutex> lock(mtx_);
            loop_edges_.insert(keyfrm);
            // cannot erase loop edges
            owner_keyfrm_->set_not_to_be_erased();
        }

        std::set<keyframe *> graph_node::get_loop_edges() const
        {