[racket] abstracting over codeblock

I'm trying to convert some old slatex'ed documents into scribble and
running into trouble.  I don't seem to have a clear enough handle on
how to use codeblock.

I can, for instance, convert

  \begin{schemedisplay}
  foo
  bar
  \end{schemedisplay}

into

  @mycode{
  foo
  bar
  }

where

  @(define(mycode . terms) (apply verbatim terms))

works fine.  However, codeblock is syntax, not a function, so I can't
just replace "verbatim" with "codeblock" above.  I can't replace
"apply verbatim" with "codeblock", either:

  string-append: expects argument of type <string>; given '("foo" "\n" "bar")

It'd be very helpful to see the mycode function such that it uses
codeblock and sets the optional line-numbering flag (#:line-numbers
<number>) to 1, say.

Thanks,
Shriram