How to use the gphoto2.gp_camera_init function in gphoto2

def open_camera(self):
        # the following needs to be changed into some
        # kind of context manager aware delay to allow
        # the camera to get ready in a context manager
        release_from_tight_grip_of_operating_system()

        ctx = gp.gp_context_new()
        error, camera = gp.gp_camera_new()
        gp.check_result(gp.gp_camera_init(camera, ctx))

        # TODO: check if camera cannot be used for some reason

        self._camera = camera
        self._context = ctx

# use Python logging
    logging.basicConfig(
        format='%(levelname)s: %(name)s: %(message)s', level=logging.WARNING)
    callback_obj = gp.check_result(gp.use_python_logging())
    # get user value
    if len(sys.argv) != 2:
        print('One command line parameter required')
        return 1
    try:
        value = int(sys.argv[1])
    except:
        print('Integer parameter required')
        return 1
    # 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'))
    # 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

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.check_result(gp.gp_camera_new())
    gp.check_result(gp.gp_camera_init(camera))
    # required configuration will depend on camera type!
    print('Checking camera config')
    # get configuration tree
    config = gp.check_result(gp.gp_camera_get_config(camera))
    # find the image format config item
    # camera dependent - 'imageformat' is 'imagequality' on some
    OK, image_format = gp.gp_widget_get_child_by_name(config, 'imageformat')
    if OK >= gp.GP_OK:
        # 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

directory_name = experiment_basename + '_gphoto2'
        self.destination = os.path.join(home_directory, directory_name)
        if os.path.exists(self.destination):
            pass
        else:
            os.mkdir(self.destination)

        # initialize the node
        rospy.init_node('gphoto2_' + nodenum)
        self.nodename = rospy.get_name().rstrip('/')
        self.nodenum = nodenum

        #gp.check_result(gp.use_python_logging())
        self.context = gp.gp_context_new()
        self.camera = gp.check_result(gp.gp_camera_new())
        gp.check_result(gp.gp_camera_init(self.camera, self.context))
        self.synchronize_camera_timestamp()
        
        self.subTrackedObjects = rospy.Subscriber('/multi_tracker/' + nodenum + '/' + topic, Float32MultiArray, self.gphoto_callback)

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.check_result(gp.gp_camera_new())
    gp.check_result(gp.gp_camera_init(camera))
    print('Getting list of files')
    files = list_files(camera)
    if not files:
        print('No files found')
        return 1
    path = files[0]
    print('Copying %s to memory' % path)
    folder, name = os.path.split(path)
    camera_file = gp.check_result(gp.gp_camera_file_get(
        camera, folder, name, gp.GP_FILE_TYPE_NORMAL))
##    # read file data using 'slurp' and a buffer allocated in Python
##    info = gp.check_result(
##        gp.gp_camera_file_get_info(camera, folder, name))
##    file_data = bytearray(info.file.size)
##    count = gp.check_result(gp.gp_file_slurp(camera_file, file_data))
##    print(count, 'bytes read')

def main():
    logging.basicConfig(
        format='%(levelname)s: %(name)s: %(message)s', level=logging.WARNING)
    callback_obj = gp.check_result(gp.use_python_logging())
    computer_files = list_computer_files()
    camera = gp.check_result(gp.gp_camera_new())
    gp.check_result(gp.gp_camera_init(camera))
    print('Getting list of files from camera...')
    camera_files = list_camera_files(camera)
    if not camera_files:
        print('No files found')
        return 1
    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):