src/vs/platform/instantiation/common/graph.ts/Graph/insertEdge
class Graph:	insertEdge(from: T, to: T): void {
		const fromNode = this.lookupOrInsertNode(from);
		const toNode = this.lookupOrInsertNode(to);

		fromNode.outgoing.set(toNode.key, toNode);
		toNode.incoming.set(fromNode.key, fromNode);
	}