\version "2.16.0"

includeOutputMode =
#(define-music-function (parser location type)(string?)
   (cond
        ((ly:get-option 'example)
             (ly:parser-include-string parser 
                 (string-append "\\include \"layout/" 
                     (string-append type ".ily\"\n"))))
        (else (ly:parser-include-string parser "\\include \"layout/a4-standalone.ily\"\n"))
   )
   (make-music 'SequentialMusic 'void #t)
)

\includeOutputMode "one-system-example"