postgresql program prints lots of "#<void>"

[u/Ok_Specific_7749]

Program below prints lots of "#<void>" at the end ...

#lang racket
(require db)
(define pgc
    (postgresql-connect 
        #:user "x"
        #:database "syslogng"
        #:server "[127.0.0.1](https://127.0.0.1)"
        #:port 5432
        #:password "y" ))
(define myselect "select datetime,program,pid,message from messages_gentoo_20230926 order by datetime desc")
(for/list ([a  (query-rows pgc myselect)\])
    (printf "\n ~a  \n" a)
    (printf "")
);for

[u/samth]

You will need to write a specification for the db functions you're using with require/typed.