fix bug in example. need to convert Value to float in Abs example
fix bug in example. need to convert Value to float in Abs example

R=adg
CC=golang-dev
http://codereview.appspot.com/2486043
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go