diff -r b632733724a8 -r 40cabcdcd2be samples/contravariance/src-impl/test/ContravarianceTest.java
--- a/samples/contravariance/src-impl/test/ContravarianceTest.java	Tue Oct 18 06:55:12 2011 +0200
+++ b/samples/contravariance/src-impl/test/ContravarianceTest.java	Thu Oct 30 21:30:10 2014 +0100
@@ -7,7 +7,6 @@
     public static void main(String[] args) {
         boolean positive = Contravariance.isPositive(10);
         boolean negative = Contravariance.isPositive(-5);
-        System.err.println("positive = " + positive + " negative = " + negative);
         assert positive : "10 is positive";
         assert !negative : "-5 is negative";
     }