in docs-content/examples-source/cdk/tree/cdk-tree-flat/cdk-tree-flat-example.ts [89:99]
getParentNode(node: ExampleFlatNode) {
const nodeIndex = TREE_DATA.indexOf(node);
for (let i = nodeIndex - 1; i >= 0; i--) {
if (TREE_DATA[i].level === node.level - 1) {
return TREE_DATA[i];
}
}
return null;
}