### Question:
SequenceSet extends LinkedNodeList<Sequence> implements Iterable<Long> { public long rangeSize() { long result = 0; Sequence sequence = getHead(); while (sequence != null) { result += sequence.range(); sequence = sequence.getNext(); } return result; }  void add(Sequence value); boolean add(long value); boolean remove(long value); long removeFirst(); Sequence removeLastSequence(); Sequence removeFirstSequence(long count); List<Sequence> getMissing(long first, long last); List<Sequence> getReceived(); boolean contains(long value); boolean contains(int first, int last); Sequence get(int value); long rangeSize(); Iterator<Long> iterator();  }### Answer:
@Test public void testRangeSize() { SequenceSet set = new SequenceSet(); set.add(1); assertEquals(1, set.rangeSize()); set.add(10); set.add(20); assertEquals(3, set.rangeSize()); set.clear(); assertEquals(0, set.rangeSize()); }