in src/visual.ts [1061:1065]
private areNodesConnected(firstNode: ForceGraphNode, secondNode: ForceGraphNode): number | boolean {
return this.data.linkedByName[firstNode.name + "," + secondNode.name]
|| this.data.linkedByName[secondNode.name + "," + firstNode.name]
|| firstNode.name === secondNode.name;
}