@Test
 public void testForEachWithIndex() {
   final int[] indexSum = new int[1];
   final MutableList<String> result = Lists.mutable.of();
   MutableList<String> source = Lists.fixedSize.of("1", "2", "3", "4", "5", "6");
   source.forEachWithIndex(
       new ObjectIntProcedure<String>() {
         public void value(String each, int index) {
           result.add(each);
           indexSum[0] += index;
         }
       });
   Assert.assertEquals(FastList.newListWith("1", "2", "3", "4", "5", "6"), result);
   Assert.assertEquals(15, indexSum[0]);
 }