\applyOutput and conditional expression

[Damian leGassick]

hi all

i'm trying to modify the example from LM 7.5.2

quote: \applyOutput context proc 

where proc is a Scheme function, taking three arguments

using the example given in LM, the following is apparently not the correct format as it throws an error  wherever i stick it, whether or not i include Staff or \Staff:

\applyOutput \Staff (define (blanker grob grob-origin context) 

(if (and (memq (ly:grob-property grob 'interfaces) 

note-head-interface) 

(eq? (ly:grob-property grob 'staff-position) 0)) 

(set! (ly:grob-property grob 'transparent) #t)))

what am i doing wrong?

also, the modification i'm after is

for(pitches = {aes, b, d})

transparent = true

anyone throw me a bone?

cheers

d