When you have an object, you may invoke its methods using the : operator.

The following would call the toString method of any kind, then print it:

println(">>> " + someObject: toString())

Of course, you may chain calls as long as a method is not of a void return type. Golo converts Java void methods by making them return null. This is neither a bug or a feature: the invokedynamic support on the JVM simply does so.