How to use the tern.command_lib.command_lib function in tern

def get_shell(image_obj, binary):
    # set up a notice origin referring to the base command library listing
    origin_command_lib = formats.invoking_base_commands
    # find the shell to invoke commands in
    shell, _ = command_lib.get_image_shell(
        command_lib.get_base_listing(binary))
    if not shell:
        # add a warning notice for no shell in the command library
        logger.warning('No shell listing in command library. '
                       'Using default shell')
        no_shell_message = errors.no_shell_listing.format(
            binary=binary, default_shell=constants.shell)
        image_obj.layers[0].origins.add_notice_to_origins(
            origin_command_lib, Notice(no_shell_message, 'warning'))
        # add a hint notice to add the shell to the command library
        add_shell_message = errors.no_listing_for_base_key.format(
            listing_key='shell')
        image_obj.layers[0].origins.add_notice_to_origins(
            origin_command_lib, Notice(add_shell_message, 'hint'))
        shell = constants.shell

def print_base_invoke(key):
    '''Given the key in the base library, return a string containing
    the command_lib/base.yml'''
    info = command_lib.get_base_listing(key)
    report = ''
    for item in command_lib.base_keys:
        if item in info.keys():
            report = report + print_invoke_list(info, item)
    report = report + '\n'
    return report

if dockerfile:
        dhelper.set_imported_layers(image_obj)
    # add notices for each layer if it is imported
    image_setup(image_obj)
    shell = ''
    # set up empty master list of packages
    master_list = []
    # find the binary by mounting the base layer
    target = rootfs.mount_base_layer(image_obj.layers[0].tar_file)
    binary = common.get_base_bin()
    # set up a notice origin referring to the base command library listing
    origin_command_lib = formats.invoking_base_commands
    # set up a notice origin for the first layer
    origin_first_layer = 'Layer: ' + image_obj.layers[0].fs_hash[:10]
    # find the shell to invoke commands in
    shell, _ = command_lib.get_image_shell(
        command_lib.get_base_listing(binary))
    if not shell:
        # add a warning notice for no shell in the command library
        logger.warning('No shell listing in command library. '
                       'Using default shell')
        no_shell_message = errors.no_shell_listing.format(
            binary=binary, default_shell=constants.shell)
        image_obj.layers[0].origins.add_notice_to_origins(
            origin_command_lib, Notice(no_shell_message, 'warning'))
        # add a hint notice to add the shell to the command library
        add_shell_message = errors.no_listing_for_base_key.format(
            listing_key='shell')
        image_obj.layers[0].origins.add_notice_to_origins(
            origin_command_lib, Notice(add_shell_message, 'hint'))
        shell = constants.shell
    # only extract packages if there is a known binary and the layer is not

def collate_list_metadata(shell, listing):
    '''Given the shell and the listing for the package manager, collect
    metadata that gets returned as a list'''
    pkg_dict = {}
    msgs = ''
    warnings = ''
    for item in command_lib.base_keys:
        if item in listing.keys():
            items, msg = command_lib.get_pkg_attr_list(shell, listing[item])
            msgs = msgs + msg
            pkg_dict.update({item: items})
        else:
            warnings = warnings + errors.no_listing_for_base_key.format(
                listing_key=item)
    return pkg_dict, msgs, warnings

def fill_package_metadata(pkg_obj, pkg_listing, shell):
    '''Given a Package object and the Package listing from the command
    library, fill in the attribute value returned from looking up the
    data and methods of the package listing.
    Fill out: version, license and proj_url
    If there are errors, fill out notices'''
    # create a NoticeOrigin for the package
    origin_str = 'command_lib/snippets.yml'
    # version
    version_listing, listing_msg = command_lib.check_library_key(
        pkg_listing, 'version')
    if version_listing:
        version_list, invoke_msg = command_lib.get_pkg_attr_list(
            shell, version_listing, package_name=pkg_obj.name)
        if version_list:
            pkg_obj.version = version_list[0]
        else:
            pkg_obj.origins.add_notice_to_origins(
                origin_str, Notice(invoke_msg, 'error'))
    else:
        pkg_obj.origins.add_notice_to_origins(
            origin_str, Notice(listing_msg, 'warning'))
    # license
    license_listing, listing_msg = command_lib.check_library_key(
        pkg_listing, 'license')
    if license_listing: