HTTP Response output port

[Retropikzel]

Hello,

on reference manual under title "Generating HTTP Responses" it says that:

"Note that response-header does not actually do anything until it is
"printed" to the standard output."

(display...) just outputs it to the servers output, not to the response.
Is there a way to obtain the port in which I could print out the
response-header? Or optionally is there a way to put them somewhere and
then, at the end of the script output the whole list with response body?

My problem is that I would like to set headers on places that do not
return to the "standard output".

- Retropikzel