diff -r 53d66ecfeb1b -r 451b5ae38b72 extensions.st
--- a/extensions.st	Fri Oct 03 02:45:16 2014 +0100
+++ b/extensions.st	Fri Oct 03 03:11:33 2014 +0100
@@ -100,6 +100,20 @@
     "Modified: / 18-12-2010 / 17:38:01 / Jan Kurs <kurs.jan@post.cz>"
 ! !
 
+!PositionableStream methodsFor:'*petitparser-core'!
+
+peekTwice
+	"Answer what would be returned if the message next were sent to the 
+	receiver. If the receiver is at the end, answer nil."
+
+	| array |
+	self atEnd 
+		ifTrue: [^Array with: nil with: nil].
+	array := Array with: (self next) with: (self peek).
+	position := position - 1.
+	^array
+! !
+
 !SequenceableCollection methodsFor:'*petitparser-core-converting'!
 
 asParser