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diff --git a/input/regression/optional-args.ly b/input/regression/optional-args.ly
new file mode 100644
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+++ b/input/regression/optional-args.ly
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+\version "2.16.0"
+
+\header{
+  texidoc= "Test optional music function arguments.
+The output is nonsensical, but if you wrack your brain,
+you'll figure it out.  Remember that optional arguments
+are matched left to right, and after the first non-match,
+the rest is skipped."
+}
+
+\layout { ragged-right = ##t }
+
+% Get following pitch into Scheme
+pitch = #(define-scheme-function (parser location p) (ly:pitch?) p)
+% The same with a duration
+dur = #(define-scheme-function (parser location p) (ly:duration?) p)
+
+% Just like \relative, but defaulting to f as reference, making the
+% first note of the music the same as if written as absolute pitch
+ablative =
+#(define-music-function (parser location ref music)
+  ((ly:pitch? #{ \pitch f #}) ly:music?)
+  #{ \relative $ref $music #})
+
+% Let's take a duration and four pitches, defaulting to 2 c' d' e'
+zap = 
+#(define-music-function (parser location dur a b c d)
+  ((ly:duration? #{ \dur 2 #}) (ly:pitch? #{ \pitch c' #})
+   (ly:pitch? #{ \pitch d' #}) (ly:pitch? #{ \pitch e' #})
+   ly:music?) #{ $a $dur $b $c ^\markup{!} $d  #})
+
+\new Voice { \relative c' e' \relative { e' } \ablative c' e' \ablative { e' }
+  \zap 8. c'' d'' {e''4..} \zap f''8 g'' \zap 4 a'' b'' c''' d'''2 }