# loop for the number of documents
  index = GPTTreeIndex.from_documents(nodes, service_context=service_context)
  indexList.append(index)
  index_summary = index.query(query_str, response_mode="tree_summarize")
  indexSummaries.append(index_summary)

graph = ComposableGraph.from_indices(
        GPTTreeIndex,
        indexList,
        index_summaries=indexSummaries,
)