def suffixed_file_name(file_path, suffix_string):
    """ Returns file path with appended string (preserving file type)

    :param file_path: (string) either relative or absolute path of file
    :param suffix_string: (string) string to append to the original file name

    :return: (string) suffixed file path

    example:
        append_path("foo.html.bar.html", "_BAZ")
        >>> "foo.html.bar.html_BAZ.html"
    """

    # reverse split, with max of 1 split:
    string_parts = file_path.rsplit('.', 1)

    return string_parts[0] + suffix_string + '.' + string_parts[1]