Attorneys at law shall not be accepted as sureties upon any official bonds provided for in section 636.4 . [S13, §358; C24, 27, 31, 35, 39, § 12755; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §682.5 ] C93, §636.5 Referred to in §636.6 , 636.7 Qualifications for sureties on probate bonds, see §633.182 Similar provision, §621.7