How to use the pgl.data_loader function in pgl

def load(name):
    if name == 'cora':
        dataset = data_loader.CoraDataset()
    elif name == "pubmed":
        dataset = data_loader.CitationDataset("pubmed", symmetry_edges=False)
    elif name == "citeseer":
        dataset = data_loader.CitationDataset("citeseer", symmetry_edges=False)
    else:
        raise ValueError(name + " dataset doesn't exists")
    return dataset

def load(name):
    if name == 'cora':
        dataset = data_loader.CoraDataset()
    elif name == "pubmed":
        dataset = data_loader.CitationDataset("pubmed", symmetry_edges=False)
    elif name == "citeseer":
        dataset = data_loader.CitationDataset("citeseer", symmetry_edges=False)
    else:
        raise ValueError(name + " dataset doesn't exists")
    return dataset

def load(name):
    if name == 'cora':
        dataset = data_loader.CoraDataset()
    elif name == "pubmed":
        dataset = data_loader.CitationDataset("pubmed", symmetry_edges=False)
    elif name == "citeseer":
        dataset = data_loader.CitationDataset("citeseer", symmetry_edges=False)
    else:
        raise ValueError(name + " dataset doesn't exists")
    return dataset

if fleet.is_worker():
        log.info("start init worker done")
        fleet.init_worker()
        #just the worker, load the sample
        log.info("init worker done")

        exe = F.Executor(F.CPUPlace())
        exe.run(fleet.startup_program)
        log.info("Startup done")

        if args.dataset is not None:
            if args.dataset == "BlogCatalog":
                graph = data_loader.BlogCatalogDataset().graph
            elif args.dataset == "ArXiv":
                graph = data_loader.ArXivDataset().graph
            else:
                raise ValueError(args.dataset + " dataset doesn't exists")
            log.info("Load buildin BlogCatalog dataset done.")
        elif args.walkpath_files is None or args.walkpath_files == "None":
            graph = build_graph(args.num_nodes, args.edge_path)
            log.info("Load graph from '%s' done." % args.edge_path)
        else:
            graph = build_fake_graph(args.num_nodes)
            log.info("Load fake graph done.")

        # bind gen
        gen_func = build_gen_func(args, graph)

        pyreader.decorate_tensor_provider(gen_func)
        pyreader.start()