Python 当我使用MITSceneParsing数据实现FCNs时，我遇到了以下错误[TypeError:'；NoneType'；对象不可下标]

我在实现完全卷积网络时使用了MITSceneParsing数据。但我得到了这个错误[TypeError:'NoneType'对象不可下标]。有人知道这个原因吗

import pickle

def read_dataset(data_dir):
    pickle_filename = "MITSceneParsing.pickle"
    pickle_filepath = os.path.join(data_dir, pickle_filename)
    if not os.path.exists(pickle_filepath):
        utils.maybe_download_and_extract(data_dir, DATA_URL, is_zipfile=True)
        SceneParsing_folder = os.path.splitext(DATA_URL.split("\\")[-1])[0]
        result = create_image_lists(os.path.join(data_dir, SceneParsing_folder))
        print("Pickling...")
        with open(pickle_filepath, 'wb') as f:
            pickle.dump(result, f, pickle.HIGHEST_PROTOCOL)
    else:
        print("Found pickle file!")

    with open(pickle_filepath, 'rb') as f:
        result = pickle.load(f)
        training_records = result['training']
        validation_records = result['validation']
        del result

    return training_records, validation_records

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