return classify(Ints.compare(left, right));
        }

        @Override
        public ComparisonChain compare(long left, long right) {
          return classify(Longs.compare(left, right));
        }

        @Override
        public ComparisonChain compare(float left, float right) {
          return classify(Float.compare(left, right));
        }

        @Override

  }

  @Override
  public int compare(@CheckForNull T left, @CheckForNull T right) {
    if (left == right) {
      return 0;
    }
    if (left == null) {
      return LEFT_IS_GREATER;
    }
    if (right == null) {
      return RIGHT_IS_GREATER;
    }
    return ordering.compare(left, right);
  }

  @Override

@SuppressWarnings({"unchecked", "rawtypes"}) // TODO(kevinb): the right way to explain this??
@ElementTypesAreNonnullByDefault
final class ReverseNaturalOrdering extends Ordering<Comparable<?>> implements Serializable {
  static final ReverseNaturalOrdering INSTANCE = new ReverseNaturalOrdering();

  @Override
  public int compare(Comparable<?> left, Comparable<?> right) {
    checkNotNull(left); // right null is caught later
    if (left == right) {

  private static class BinaryNode {
    final int x;
    final Optional<BinaryNode> left;
    final Optional<BinaryNode> right;

    BinaryNode(int x, Optional<BinaryNode> left, Optional<BinaryNode> right) {
      this.x = x;
      this.left = left;
      this.right = right;
    }
  }

  enum Topology {
    BALANCED {
      @Override
      Optional<BinaryNode> createTree(int size, Random rng) {

    }
  }

  private static Character[] concat(Character[] left, Character[] right) {
    Character[] result = new Character[left.length + right.length];
    System.arraycopy(left, 0, result, 0, left.length);
    System.arraycopy(right, 0, result, left.length, right.length);
    return result;
  }

      return asList(all).subList(2, elements.length + 2);
    }
  }

  private static Double[] concat(Double[] left, Double[] right) {
    Double[] result = new Double[left.length + right.length];
    System.arraycopy(left, 0, result, 0, left.length);
    System.arraycopy(right, 0, result, left.length, right.length);
    return result;
  }

  public abstract static class TestDoubleListGenerator implements TestListGenerator<Double> {

    }
  }

  private static Character[] concat(Character[] left, Character[] right) {
    Character[] result = new Character[left.length + right.length];
    System.arraycopy(left, 0, result, 0, left.length);
    System.arraycopy(right, 0, result, left.length, right.length);
    return result;
  }

          accum = collector.combiner().apply(accum, newAccum);
        }
        return accum;
      }
    },
    /** Get one accumulator for each element and merge the accumulators right-to-left. */
    MERGE_RIGHT_ASSOCIATIVE {
      @Override
      final <T extends @Nullable Object, A extends @Nullable Object, R extends @Nullable Object>
          A result(Collector<T, A, R> collector, Iterable<T> inputs) {

      return asList(all).subList(2, elements.length + 2);
    }
  }

  private static Long[] concat(Long[] left, Long[] right) {
    Long[] result = new Long[left.length + right.length];
    System.arraycopy(left, 0, result, 0, left.length);
    System.arraycopy(right, 0, result, left.length, right.length);
    return result;
  }

  public abstract static class TestLongListGenerator implements TestListGenerator<Long> {

    }

    private void assertVersionOlder(String left, String right) {
        assertTrue(
                newArtifactVersion(left).compareTo(newArtifactVersion(right)) < 0,
                left + " should be older than " + right);
        assertTrue(
                newArtifactVersion(right).compareTo(newArtifactVersion(left)) > 0,
                right + " should be newer than " + left);
    }