How do I generate a \break from within scheme?

[Karl Hammar]

In example below:

\version "2.4.2"

#(define a "satb")
#(define (br x) (if (equal? x a) (write "\\break")))
%#(define (br x) (if (equal? x a) (make-music 'BreakEvent)))
%#(define (br x) (if (equal? x a) #{ \break #} ))

asd = \relative g' {
  g1 |
  #(br "satb")
  %\tag #'(satb) { \break }
  g1 |
}

%\keepWithTag #'satb
\score {
 \keepWithTag #'satb \new Staff \asd
}

I can use tags to get conditional \break's.
Unfortunately I cannot put the \keepWithTag before the \score,
so when I have a lot of staves, I cannot change tagname in one place.

In the manual about the \break I can see it has name 'BreakEvent, 
syntax \break,
it is an event of type break-event.

What should I replace the (write "\\break") with to generate a line 
break in the score.

Regards,
/Karl