Task Description: Graph Neural Networks stack multiple message passing layers to expand their receptive field. Click on a node to trace its calculations. Notice how changing the operator changes how features propagate from 1-hop away in Layer 1 ($h^{(1)}$) to 2-hops away in Layer 2 ($h^{(2)}$). For instance, under Sum aggregation, Node D can now detect Node A's original features via the path $A \rightarrow B \rightarrow D$.