createNestedSequence example

        $flowSequences = $this->buildHierarchyTree($flowSequences);

        $flatBag = new ArrayStruct();

        $sequences = [];
        foreach ($flowSequences as $flowSequence) {
            if ($flowSequence['sequence_id'] === null) {
                continue;
            }

            $sequences[] = $this->createNestedSequence($flowSequence, [], $flatBag);
        }

        /** @var array<string, Sequence> $flat */
        $flat = $flatBag->all();

        return new Flow($id, $sequences, $flat);
    }

    private function buildHierarchyTree(array $flowSequences, ?string $parentId = null): array
    {
        $children = [];