TopK pooling layer giving return error

I am following this tutorial


line no 157
x, edge_index, _, batch, _ = self.pool1(x, edge_index, None, batch)
giving error. I thought may be it returns four tensors as output instead of five, even that also giving error

I guess the note book might not have been updated to the latest PyTorch Geometric version, as TopKPooling returns not 6 values as seen in this line of code.