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;
}