How to use the gphoto2.gp_camera_set_config function in gphoto2

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'))
    # check value in range
    count = gp.check_result(gp.gp_widget_count_choices(capture_target))
    if value < 0 or value >= count:
        print('Parameter out of range')
        return 1
    # set value
    value = gp.check_result(gp.gp_widget_get_choice(capture_target, value))
    gp.check_result(gp.gp_widget_set_value(capture_target, value))
    # set config
    gp.check_result(gp.gp_camera_set_config(camera, config))
    # clean up
    gp.check_result(gp.gp_camera_exit(camera))
    return 0

# get current setting
        value = gp.check_result(gp.gp_widget_get_value(image_format))
        # make sure it's not raw
        if 'raw' in value.lower():
            print('Cannot preview raw images')
            return 1
    # find the capture size class config item
    # need to set this on my Canon 350d to get preview to work at all
    OK, capture_size_class = gp.gp_widget_get_child_by_name(
        config, 'capturesizeclass')
    if OK >= gp.GP_OK:
        # set value
        value = gp.check_result(gp.gp_widget_get_choice(capture_size_class, 2))
        gp.check_result(gp.gp_widget_set_value(capture_size_class, value))
        # set config
        gp.check_result(gp.gp_camera_set_config(camera, config))
    # capture preview image (not saved to camera memory card)
    print('Capturing preview image')
    camera_file = gp.check_result(gp.gp_camera_capture_preview(camera))
    file_data = gp.check_result(gp.gp_file_get_data_and_size(camera_file))
    # display image
    data = memoryview(file_data)
    print(type(data), len(data))
    print(data[:10].tolist())
    image = Image.open(io.BytesIO(file_data))
    image.show()
    gp.check_result(gp.gp_camera_exit(camera))
    return 0

# get current setting
        value = gp.check_result(gp.gp_widget_get_value(image_format))
        # make sure it's not raw
        if 'raw' in value.lower():
            app.logger.debug('Cannot preview raw images')
            return 1
    # find the capture size class config item
    # need to set this on my Canon 350d to get preview to work at all
    OK, capture_size_class = gp.gp_widget_get_child_by_name(
        config, 'capturesizeclass')
    if OK >= gp.GP_OK:
        # set value
        value = gp.check_result(gp.gp_widget_get_choice(capture_size_class, 2))
        gp.check_result(gp.gp_widget_set_value(capture_size_class, value))
        # set config
        gp.check_result(gp.gp_camera_set_config(camera, config))
    # capture preview image (not saved to camera memory card)
    app.logger.debug('Capturing preview image')
    camera_file = gp.check_result(gp.gp_camera_capture_preview(camera))
    file_data = gp.check_result(gp.gp_file_get_data_and_size(camera_file))
    # display image
    data = memoryview(file_data)
    app.logger.debug(type(data), len(data))
    app.logger.debug(data[:10].tolist())
    fileName = os.path.join(PI_PREVIEW_DIR, PI_PREVIEW_FILE)
    if os.path.exists(fileName):
        os.remove(fileName)
    Image.open(io.BytesIO(file_data)).save(fileName, "JPEG")
    return 0

# get current setting
        value = gp.check_result(gp.gp_widget_get_value(image_format))
        # make sure it's not raw
        if 'raw' in value.lower():
            app.logger.debug('Cannot preview raw images')
            return 1
    # find the capture size class config item
    # need to set this on my Canon 350d to get preview to work at all
    OK, capture_size_class = gp.gp_widget_get_child_by_name(
        config, 'capturesizeclass')
    if OK >= gp.GP_OK:
        # set value
        value = gp.check_result(gp.gp_widget_get_choice(capture_size_class, 2))
        gp.check_result(gp.gp_widget_set_value(capture_size_class, value))
        # set config
        gp.check_result(gp.gp_camera_set_config(camera, config))
    # capture preview image (not saved to camera memory card)
    app.logger.debug('Capturing preview image')
    camera_file = gp.check_result(gp.gp_camera_capture_preview(camera))
    file_data = gp.check_result(gp.gp_file_get_data_and_size(camera_file))
    # display image
    data = memoryview(file_data)
    app.logger.debug(type(data), len(data))
    app.logger.debug(data[:10].tolist())
    fileName = os.path.join(PI_PREVIEW_DIR, PI_PREVIEW_FILE)
    if os.path.exists(fileName):
        os.remove(fileName)
    Image.open(io.BytesIO(file_data)).save(fileName, "JPEG")
    return 0