How to use the gphoto2.check_result function in gphoto2

logging.basicConfig(
        format='%(levelname)s: %(name)s: %(message)s', level=logging.WARNING)
    callback_obj = gp.check_result(gp.use_python_logging())
    # open camera connection
    camera = gp.check_result(gp.gp_camera_new())
    gp.check_result(gp.gp_camera_init(camera))
    # get configuration tree
    config = gp.check_result(gp.gp_camera_get_config(camera))
    # find the capture target config item
    capture_target = gp.check_result(
        gp.gp_widget_get_child_by_name(config, 'capturetarget'))
    # print current setting
    value = gp.check_result(gp.gp_widget_get_value(capture_target))
    print('Current setting:', value)
    # print possible settings
    for n in range(gp.check_result(gp.gp_widget_count_choices(capture_target))):
        choice = gp.check_result(gp.gp_widget_get_choice(capture_target, n))
        print('Choice:', n, choice)
    # clean up
    gp.check_result(gp.gp_camera_exit(camera))
    return 0

# add our own callback, with data
    print('Using Python callback, with data')
    print('================================')
    callback_obj = gp.check_result(
        gp.gp_log_add_func(gp.GP_LOG_VERBOSE, callback, 'some data'))
    print('callback_obj', callback_obj)
    # create an error
    gp.gp_camera_init(camera)
    # uninstall callback
    del callback_obj
    # set gphoto2 to use Python's logging directly
    print('Using Python logging')
    print('====================')
    logging.basicConfig(
        format='%(levelname)s: %(name)s: %(message)s', level=logging.WARNING)
    callback_obj = gp.check_result(gp.use_python_logging())
    # create an error
    gp.gp_camera_init(camera)
    return 0

def main():
    logging.basicConfig(
        format='%(levelname)s: %(name)s: %(message)s', level=logging.WARNING)
    callback_obj = gp.check_result(gp.use_python_logging())
    camera = gp.Camera()
    camera.init()
    print('Capturing image')
    file_path = camera.capture(gp.GP_CAPTURE_IMAGE)
    print('Camera file path: {0}/{1}'.format(file_path.folder, file_path.name))
    target = os.path.join('/tmp', file_path.name)
    print('Copying image to', target)
    camera_file = camera.file_get(
        file_path.folder, file_path.name, gp.GP_FILE_TYPE_NORMAL)
    camera_file.save(target)
    subprocess.call(['xdg-open', target])
    camera.exit()
    return 0

print('Copying files...')
    for path in camera_files:
        info = get_camera_file_info(camera, path)
        timestamp = datetime.fromtimestamp(info.file.mtime)
        folder, name = os.path.split(path)
        dest_dir = get_target_dir(timestamp)
        dest = os.path.join(dest_dir, name)
        if dest in computer_files:
            continue
        print('%s -> %s' % (path, dest_dir))
        if not os.path.isdir(dest_dir):
            os.makedirs(dest_dir)
        camera_file = gp.check_result(gp.gp_camera_file_get(
            camera, folder, name, gp.GP_FILE_TYPE_NORMAL))
        gp.check_result(gp.gp_file_save(camera_file, dest))
    gp.check_result(gp.gp_camera_exit(camera))
    return 0

def list_camera_files(camera, path='/'):
    """ Returns a list of all the image files on the camera """
    result = []
    # get files
    for name, value in gp.check_result(
            gp.gp_camera_folder_list_files(camera, path)):
        result.append(os.path.join(path, name))
    # read folders
    folders = []
    for name, value in gp.check_result(
            gp.gp_camera_folder_list_folders(camera, path)):
        folders.append(name)
    # recurse over subfolders
    for name in folders:
        result.extend(list_camera_files(camera, os.path.join(path, name)))
    return result