def format_rotor_key_defs(rotor_keyword_vals):
    """ Formats strings that contain the 'Group', 'Axis', and 'Symmetry'
        keywords and values that are used to define hindered rotors and
        internal rotors in MESS input files.

        :param rotor_keyword_vals: values for the for some rotor keyword
        :type: rotor_keyword_vals: list(int)
        :return rotor_keyword_str: MESS-format string containing values
        :rtype str
    """

    # Build string containing the values of each keyword
    rotor_keyword_str = ''
    for vals in rotor_keyword_vals:
        rotor_keyword_str += '{0:<4d}'.format(vals+1)

    return rotor_keyword_str