### Question:
NoOpTruncator implements VectorTruncator, Serializable { @Override public Long2DoubleMap truncate(Long2DoubleMap v) { return LongUtils.frozenMap(v); }  @Override Long2DoubleMap truncate(Long2DoubleMap v);  }### Answer:
@Test public void testSimpleTruncate() { long[] keys = {1, 2, 3, 4}; double[] values = {1.0, 2.0, 3.0, 4.0}; Long2DoubleSortedArrayMap v = Long2DoubleSortedArrayMap.wrapUnsorted(keys, values); VectorTruncator truncator = new NoOpTruncator(); Long2DoubleMap v2 = truncator.truncate(v); long i = 1; for (Long2DoubleMap.Entry e: v2.long2DoubleEntrySet()) { assertThat(e.getLongKey(), equalTo(i)); assertThat(e.getDoubleValue(), closeTo(i, EPSILON)); i++; } assertThat(i, equalTo(5L)); }