code: public VertexElement addVertexElement(Schema.BaseType baseType) {
          Vertex vertex = graph.addVertex(baseType.name());
          return new VertexElement(tx, vertex);
      }
docs: Creates a new Vertex in the graph and builds a VertexElement which wraps the newly created vertex
  @param baseType   The Schema.BaseType
  @return a new VertexElement