def METHOD_NAME(self, node: JoinToBaseOutputNode) -> DefaultCost:  # noqa: D
    parent_costs = [x.accept(self) for x in node.parent_nodes]
    # Add number of joins to the cost.
    node_cost = DefaultCost(num_joins=len(node.join_targets))
    return DefaultCost.sum(parent_costs + [node_cost])