Get reference to actual label of vertex. Vertex labels are matched using their equals method, which may or may not test for actual equivalence. Result remains part of graph. The label of the vertex sought. The actual label, or null if none is found.
Edge is identified by the labels on associated vertices.
If edge is directed, the label1 indicates source. Test for vertex membership. True iff vertex with matching label is found. If edges are directed, vLabel1 indicates source. True iff the edge exists within the graph.