my $start = q{AA};
    my $next  = q{AB};
    my $count = 0;
    my $value;
    foreach my $entry ( @{$strings} ) {
        if ( $count == $#$strings ) {
            $next = q{$};
        }
        else {
            $next = q{\,\ } . _alpha_add($start);
        }
        $affiliation_string =~ m/$start\((.*?)\)($next)/s;
        $value                     = $1;
        $affiliation_key->{$entry} = $value;
        $start                     = _alpha_add($start);
        $next                      = _alpha_add($next);
        $count++;
    }

##</code><code>##

sub _alpha_add {
    my $string = shift;
    if ( substr( $string, 1, 1 ) eq q{Z} ) {
        my $first_character  = substr( $string, 0, 1 );
        my $second_character = substr( $string, 1, 1 );
        $first_character++;
        $second_character = q{A};
        $string = $first_character . $second_character;
    }
    else {
        $string++;
    }
    return $string;
}