(doc help) scheme: why not start with define-music-function ?

[Graham Percival]

In the current manual, define-music-function is introduced late in the 
scheme chapter.  I suspect that this is simply because 
define-music-function is a more recent lilypond construct, and whoever 
added it didn't want to disturb the existing material.  Is that 
correct?

I'm revising the chapter now (as you can tell from the previous 
half-dozen emails :), and it makes sense to me to _begin_ the chapter 
with define-music-function, and then work through the general theory of 
scheme, lilypond music expressions, etc.  In other words, stick the 
define-music-function stuff *before* the current 11.1.1.  Are there any 
objections?  I really don't think that people need to know what 
#(ly:make-music-function  (11.1.3) does before using 
define-music-function, but I still can't claim to fully understand 
#(ly:make-music-function  myself, so I might be missing some vital 
info.

My current sense is that define-music-function and \displayMusic (and 
perhaps a bit of patience) are the most important parts of 11.1.  
Thoughts?

Cheers,
- Graham