A problem of GraphSAGE

[yangfeizZZ]

Hello author:
When i run:
unsupervised_samples = UnsupervisedSampler(G, nodes=nodes, length=length, number_of_walks=number_of_walks, seed=42)
graphsage = GraphSAGE(layer_sizes=layer_sizes, generator=train_gen, aggregator=AttentionalAggregator, bias=True,
dropout=0.0, normalize="l2", kernel_regularizer='l1')"
layer_sizes = [50, 50]
assert len(layer_sizes) == len(num_samples)
the error is occurring.
The error is "TypeError: Generator should be an instance of GraphSAGENodeGenerator or GraphSAGELinkGenerator"
Please,how to resolve it?