def get_classes_in_image(xml_file_list):
    classes_in_data_set = set()

    for xml_file_path in xml_file_list:
        with open(xml_file_path, 'r') as file:
            xml_file = xmltodict.parse(file.read())

            objects = xml_file['annotation']['object']
            
            # 항상 리스트 형태로 처리하기 위해 단일 객체도 리스트로 변환
            if not isinstance(objects, list):
                objects = [objects]
            
            for obj in objects:
                classes_in_data_set.add(obj['name'].lower())

    classes_in_data_set = sorted(classes_in_data_set) 
    print(classes_in_data_set)
    return classes_in_data_set
classes_inDataSet = get_classes_in_image(test_xml_file_path_list)