code: from llama_index.core import KnowledgeGraphIndex
  from llama_index.core import StorageContext, load_index_from_storage
  import llama_index.core
  llama_index.core.set_global_handler("langfuse")
  
  
  # rebuild storage context
  storage_context = StorageContext.from_defaults(persist_dir="math_index_persist")
  
  # load index
  query_engine = load_index_from_storage(storage_context).as_query_engine()
  
  # query
  query = "What are two prominent early number theorists?"
  result = query_engine.query(query)
  print(result)
apis: llama_index.core.StorageContext.from_defaults llama_index.core.load_index_from_storage
extract_api: [((236, 298), 'llama_index.core.StorageContext.from_defaults', 'StorageContext.from_defaults', ([], {'persist_dir': '"""math_index_persist"""'}), "(persist_dir='math_index_persist')\n", (264, 298), False, 'from llama_index.core import StorageContext, load_index_from_storage\n'), ((328, 368), 'llama_index.core.load_index_from_storage', 'load_index_from_storage', (['storage_context'], {}), '(storage_context)\n', (351, 368), False, 'from llama_index.core import StorageContext, load_index_from_storage\n')]