In http://docs.oracle.com/javase/tutorial/java/javaOO/QandE/nested-questions.html

Define a method named print(java.util.Function<Integer, Boolean> iterator) that performs the same function as print(DataStructureIterator iterator). Invoke this method with a lambda expression to print elements that have an even index value. Invoke this method again with a lambda expression to print elements that have an odd index value.

print(java.util.Function<Integer, Boolean> iterator) -> print(java.util.function.Function<Integer, Boolean> iterator)