How to use the jupyterlab.jupyterlab.commands.pjoin function in jupyterlab

info = get_app_info(app_dir)
    public_url = info['publicUrl']
    user_settings_dir = getattr(
        nbapp, 'user_settings_dir', get_user_settings_dir()
    )
    workspaces_dir = getattr(nbapp, 'workspaces_dir', get_workspaces_dir())

    config = LabConfig()
    config.app_dir = app_dir
    config.app_name = 'JupyterLab'
    config.app_namespace = 'jupyterlab'
    config.app_settings_dir = pjoin(app_dir, 'settings')
    config.app_version = info['version']
    config.cache_files = True
    config.schemas_dir = pjoin(app_dir, 'schemas')
    config.templates_dir = pjoin(app_dir, 'static')
    config.themes_dir = pjoin(app_dir, 'themes')
    config.user_settings_dir = user_settings_dir
    config.workspaces_dir = workspaces_dir

    if getattr(nbapp, 'override_static_url', ''):
        public_url = nbapp.override_static_url
    if getattr(nbapp, 'override_theme_url', ''):
        config.themes_url = nbapp.override_theme_url
        config.themes_dir = ''

    if public_url:
        config.public_url = public_url
    else:
        config.static_dir = pjoin(app_dir, 'static')

    return config

pjoin
    )

    app_dir = getattr(nbapp, 'app_dir', get_app_dir())
    info = get_app_info(app_dir)
    public_url = info['publicUrl']
    user_settings_dir = getattr(
        nbapp, 'user_settings_dir', get_user_settings_dir()
    )
    workspaces_dir = getattr(nbapp, 'workspaces_dir', get_workspaces_dir())

    config = LabConfig()
    config.app_dir = app_dir
    config.app_name = 'JupyterLab'
    config.app_namespace = 'jupyterlab'
    config.app_settings_dir = pjoin(app_dir, 'settings')
    config.app_version = info['version']
    config.cache_files = True
    config.schemas_dir = pjoin(app_dir, 'schemas')
    config.templates_dir = pjoin(app_dir, 'static')
    config.themes_dir = pjoin(app_dir, 'themes')
    config.user_settings_dir = user_settings_dir
    config.workspaces_dir = workspaces_dir

    if getattr(nbapp, 'override_static_url', ''):
        public_url = nbapp.override_static_url
    if getattr(nbapp, 'override_theme_url', ''):
        config.themes_url = nbapp.override_theme_url
        config.themes_dir = ''

    if public_url:
        config.public_url = public_url

public_url = info['publicUrl']
    user_settings_dir = getattr(
        nbapp, 'user_settings_dir', get_user_settings_dir()
    )
    workspaces_dir = getattr(nbapp, 'workspaces_dir', get_workspaces_dir())

    config = LabConfig()
    config.app_dir = app_dir
    config.app_name = 'JupyterLab'
    config.app_namespace = 'jupyterlab'
    config.app_settings_dir = pjoin(app_dir, 'settings')
    config.app_version = info['version']
    config.cache_files = True
    config.schemas_dir = pjoin(app_dir, 'schemas')
    config.templates_dir = pjoin(app_dir, 'static')
    config.themes_dir = pjoin(app_dir, 'themes')
    config.user_settings_dir = user_settings_dir
    config.workspaces_dir = workspaces_dir

    if getattr(nbapp, 'override_static_url', ''):
        public_url = nbapp.override_static_url
    if getattr(nbapp, 'override_theme_url', ''):
        config.themes_url = nbapp.override_theme_url
        config.themes_dir = ''

    if public_url:
        config.public_url = public_url
    else:
        config.static_dir = pjoin(app_dir, 'static')

    return config

app_dir = getattr(nbapp, 'app_dir', get_app_dir())
    info = get_app_info(app_dir)
    public_url = info['publicUrl']
    user_settings_dir = getattr(
        nbapp, 'user_settings_dir', get_user_settings_dir()
    )
    workspaces_dir = getattr(nbapp, 'workspaces_dir', get_workspaces_dir())

    config = LabConfig()
    config.app_dir = app_dir
    config.app_name = 'JupyterLab'
    config.app_namespace = 'jupyterlab'
    config.app_settings_dir = pjoin(app_dir, 'settings')
    config.app_version = info['version']
    config.cache_files = True
    config.schemas_dir = pjoin(app_dir, 'schemas')
    config.templates_dir = pjoin(app_dir, 'static')
    config.themes_dir = pjoin(app_dir, 'themes')
    config.user_settings_dir = user_settings_dir
    config.workspaces_dir = workspaces_dir

    if getattr(nbapp, 'override_static_url', ''):
        public_url = nbapp.override_static_url
    if getattr(nbapp, 'override_theme_url', ''):
        config.themes_url = nbapp.override_theme_url
        config.themes_dir = ''

    if public_url:
        config.public_url = public_url
    else:
        config.static_dir = pjoin(app_dir, 'static')

config.schemas_dir = pjoin(app_dir, 'schemas')
    config.templates_dir = pjoin(app_dir, 'static')
    config.themes_dir = pjoin(app_dir, 'themes')
    config.user_settings_dir = user_settings_dir
    config.workspaces_dir = workspaces_dir

    if getattr(nbapp, 'override_static_url', ''):
        public_url = nbapp.override_static_url
    if getattr(nbapp, 'override_theme_url', ''):
        config.themes_url = nbapp.override_theme_url
        config.themes_dir = ''

    if public_url:
        config.public_url = public_url
    else:
        config.static_dir = pjoin(app_dir, 'static')

    return config