boon/src/main/java/org/boon/Maps.java
@Universal
    public static <K, V> V after( NavigableMap<K, V> map, final K index ) {
        return map.get( map.higherKey( index ) );
    }
@Universal
    public static <K, V> V after( NavigableMap<K, V> map, final K index ) {
        return map.get( map.higherKey( index ) );
    }
Grabs the value after this key from a tree map (Navigable map).