/guava/android/guava/src/com/google/common/collect/StandardRowSortedTable.java
checkNotNull ( toKey ) ;
@Override public R lastKey() { return sortedBackingMap().lastKey(); } @Override public SortedMap<R, Map<C, V>> headMap(R toKey) { <extra_id_0> return new StandardRowSortedTable<R, C, V>(sortedBackingMap().headMap(toKey), factory) .rowMap(); } @Override public SortedMap<R, Map<C, V>> subMap(R fromKey, R toKey) { checkNotNull(fromKey);