Validator should check for required files

    return parser.parse_args()

def check_required_files(dir_to_validate):

    """Check if required files exists."""

    REQUIRED_FILES = ["01-*.md",

                      "discussion.md",

                      "index.md",

                      "instructors.md",

                      "LICENSE.md",

                      "motivation.md",

                      "README.md",

                      "reference.md"]

    valid = True

    for required in REQUIRED_FILES:

        req_fn = os.path.join(dir_to_validate, required)

        if not glob.glob(req_fn):

            logging.error(

                "Missing file {0}.".format(required))

            valid = False

    return valid

def get_files_to_validate(file_or_path):

    """Generate list of files to validate."""

    files_to_validate = []

    dir_to_validate = None

    for fn in file_or_path:

        if os.path.isdir(fn):

            search_str = os.path.join(fn, "*.md")

            files_to_validate.extend(glob.glob(search_str))

            dir_to_validate = fn

        elif os.path.isfile(fn):

            files_to_validate.append(fn)

        else:

            logging.error(

                "The specified file or folder {0} does not exist; "

                "could not perform validation".format(fn))

    return files_to_validate, dir_to_validate

def main(parsed_args_obj):

    if parsed_args_obj.debug:

    template = parsed_args_obj.template

    all_valid = True

    for fn in parsed_args_obj.file_or_path:

        if os.path.isdir(fn):

            res = validate_folder(fn, template=template)

        elif os.path.isfile(fn):

    files_to_validate, dir_to_validate = get_files_to_validate(parsed_args_obj.file_or_path)

    # If user ask to validate only one file don't check for required files.

    if dir_to_validate:

        all_valid = all_valid and check_required_files(dir_to_validate)

    for fn in files_to_validate:

        res = validate_single(fn, template=template)

        else:

            res = False

            logging.error(

                "The specified file or folder {0} does not exist; "

                "could not perform validation".format(fn))

        all_valid = all_valid and res