* @return the extended Pipeline
*/
public GremlinPipeline<S, Vertex> in(final int branchFactor, final String... labels) {
return this.doQueryOptimization ?
this.add(new VertexQueryPipe(Vertex.class, Direction.IN, null, null, branchFactor, 0, Integer.MAX_VALUE, labels)) :
this.add(new InPipe(branchFactor, labels));
}