Scheme for verbatim display of ly:music argument

[Robert Schmaus]

Dear all,

I'd like to create a scheme function with one ly:music argument which 
does the following: insert the music expression at the current place and 
display the source code (ie the argument passed to the function) 
verbatim above the respective place in the score.
And I need to use that in a ChordNames context.

Thus, I'd like to have the following:

<<
        \new ChordNames {
                \chordmode{  \fn{ c1:7.5+ } \fn{ c1:maj7.9 }  }
        }
>>

should produce something like

c1:7.5+    c1:maj7.9
C7(#5)   | Cmaj9


Just passing the music expression is easy:

fn = #(define-music-function (parser location myChord) (ly:music?)
        #{
                $myChord
        #}
)

Is it possible to add a markup part to display myChord verbatim?

Thanks in advance!
Best,
Robert