Completing exercises for Chapter 2.

The Java 8 functional interfaces include `#compose` and `#andThen` for composing functions like this. You can:

```java
private static BiFunction<Boolean, Boolean, Stream<Integer>> getValuesAsInteger = 
    getValues.andThen( bools -> bools.mapToInt( bool -> bool ? 1 : 0 ).boxed() );
```