program strip_comments;
    print(strip(";#", "apples, pears # and bananas"));
    print(strip(";#", "apples, pears ; and bananas"));
    print(strip(";#", "apples, pears"));

    proc strip(comment_chars, s);
        if exists c = s(i) | c in comment_chars then
            s := s(..i-1);
        end if;
        rspan(s, "\n\t ");
        return s;
    end proc;
end program;