Number of pages output

[Andrew Black - lists]

Is it possible to print out the number of pages that Lilypond has output 
to a PDF.

Or even better, can you add a check in the code that you are on the page 
you expect (a bit like barNumberCheck).  So I could put
  \pageNumberCheck  2
at the end of part and if it has spilled onto 3 pages I can investigate.