439     SSVertex(Vertex* v) : fVertex(v), fPrev(nullptr), fNext(nullptr) {}  in SSVertex()
440     Vertex* fVertex;  member
517     Vertex* prev = e->fPrev->fVertex;  in create_event()
518     Vertex* next = e->fNext->fVertex;  in create_event()
1472                 edge->fPrev->fVertex->fID,  in dump_skel()
1473                 edge->fNext->fVertex->fID);  in dump_skel()
1800     Vertex* prev = fEdge->fPrev->fVertex;  in apply()
1801     Vertex* next = fEdge->fNext->fVertex;  in apply()
1831         ss_connect(prevEdge->fPrev->fVertex, dest, c, alloc);  in apply()
1840             create_event(prevEdge, prevEdge->fPrev->fVertex, nextEdge, dest, events, c, alloc);  in apply()
1841             create_event(nextEdge, nextEdge->fNext->fVertex, prevEdge, dest, events, c, alloc);  in apply()
1933             connect(edge->fPrev->fVertex, edge->fNext->fVertex, e->fType, c, alloc, 0);  in collapse_overlap_regions()