--- a/PeekableStream.st	Thu Nov 24 06:40:21 2016 +0100
+++ b/PeekableStream.st	Fri Nov 25 07:07:27 2016 +0100
@@ -125,6 +125,12 @@
     "Modified: / 23-10-2006 / 16:33:40 / cg"
 ! !
 
+!PeekableStream class methodsFor:'testing'!
+
+isAbstract
+    ^ self == PeekableStream
+! !
+
 !PeekableStream methodsFor:'chunk input/output'!
 
 nextChunk