### Question:
Tuples { public static <K, V> Mapper<Pair<K, V>, Map.Entry<K, V>> toMapEntry() { return new Mapper<Pair<K, V>, Map.Entry<K, V>>() { @Override public Map.Entry<K, V> map(Pair<K, V> pair) { return mapEntryFor(pair); } }; }  static Mapper<Pair<K, V>, Map.Entry<K, V>> toMapEntry(); static Iterable<T> firsts(Iterable<? extends First<T>> firstables); static Iterable<T> seconds(Iterable<? extends Second<T>> secondables); static Iterable<T> thirds(Iterable<? extends Third<T>> thirdables); static Iterable<T> fourths(Iterable<? extends Fourth<T>> fourthables); static Iterable<T> fifths(Iterable<? extends Fifth<T>> fifthables); static Iterable<T> sixths(Iterable<? extends Sixth<T>> sixthable); static Iterable<T> sevenths(Iterable<? extends Seventh<T>> seventhable); static Iterable<T> eighths(Iterable<? extends Eighth<T>> eighthables); static Iterable<T> ninths(Iterable<? extends Ninth<T>> ninthables); static Mapper<? super First<T>, T> toFirst(); static Mapper<? super Second<T>, T> toSecond(); static Mapper<? super Third<T>, T> toThird(); static Mapper<? super Fourth<T>, T> toFourth(); static Mapper<? super Fifth<T>, T> toFifth(); static Mapper<? super Sixth<T>, T> toSixth(); static Mapper<? super Seventh<T>, T> toSeventh(); static Mapper<? super Eighth<T>, T> toEighth(); static Mapper<? super Ninth<T>, T> toNinth();  }### Answer:
@Test public void shouldConvertPairToMapEntryWithKeyAsFirstValueAsSecond() throws Exception { Pair<String, Integer> pair = tuple("string", 100); Map.Entry<String, Integer> actual = new AbstractMap.SimpleImmutableEntry<String, Integer>("string", 100); Mapper<Pair<String, Integer>, Map.Entry<String, Integer>> toMapEntry = Tuples.toMapEntry(); Map.Entry<String, Integer> expected = toMapEntry.map(pair); assertThat(actual, is(expected)); }