def get_lines_with_empty_keywords(file_path: str) -> set:
    """
    Identifies lines in the file that are empty.
    :param file_path: path to keywords file
    :return: set of lines that are empty
    """
    empty_keywords = set()
    with open(file_path, "r") as file_obj:
        line_number = -1
        for line in file_obj:
            line = line.rstrip()
            line_number += 1
            if len(line) == 0:
                empty_keywords.add(line_number)
    return empty_keywords