All electors must personally mark or designate their choices on the vote-by-mail ballot, except:(1) Electors who require assistance to vote because of blindness, disability, or inability to read or write, who may have some person of the elector’s choice, other than the elector’s employer, an agent of the employer, or an officer or agent of the elector’s union, mark the elector’s choices or assist the elector in marking his or her choices on the ballot.