   let node = {
                            test: test_children,
                            name: parent.name ? parent.name + test_name : test_name,
                            overlaps: new Map(parent.overlaps), // map: span_id -> OVERLAP
                            children: new Map(), // map: index -> struct
                            is_leaf: test_children.length == 0,
                        };
                        parent.children.set(index, node);
                    }

                    // Now