dependentCount method
How many nodes currently depend on node — the size of its reverse edge
set.
The observable the disposal contract is written against: a subscribe/unsubscribe cycle that disposes what it creates must leave this at its starting value no matter how many cycles run. Returns 0 for a disposed node.
Implementation
int dependentCount(AsyncGraphNode node) {
if (_isDisposedNode(node)) return 0;
return _dependents[node]?.length ?? 0;
}