(a, b) -> {
          count.incrementAndGet();
          assertThat(a.equals(String.valueOf(b))).isTrue();
        });
    assertThat(count.get()).isEqualTo(100000);
    // of course, this test doesn't prove that anything actually happened in parallel...
  }

  // TODO(kevinb): switch to importing Truth's assertThat(DoubleStream) if we get that added
  private static IterableSubject assertThatDoubleStream(DoubleStream stream) {

TensorFlow coding style.

#### General guidelines and philosophy for contribution

*   Include unit tests when you contribute new features, as they help to a)
    prove that your code works correctly, and b) guard against future breaking
    changes to lower the maintenance cost.
*   Bug fixes also generally require unit tests, because the presence of bugs

      // even though K doesn't explicitly implement Comparable.
      comparator = (Comparator<? super K>) NATURAL_ORDER;
    }
    if (map instanceof ImmutableSortedMap) {
      // TODO(kevinb): Prove that this cast is safe, even though
      // Collections.unmodifiableSortedMap requires the same key type.
      @SuppressWarnings("unchecked")
      ImmutableSortedMap<K, V> kvMap = (ImmutableSortedMap<K, V>) map;

        verifyScenario(alteration.mutate(scenario), level + 1);
      }
    }
  }

  /**
   * An aggregation of an ordering with a list (of size > 1) that should prove to be in strictly
   * increasing order according to that ordering.
   */
  private static class Scenario<T extends @Nullable Object> {
    final Ordering<T> ordering;
    final List<T> strictlyOrderedList;

        verifyScenario(alteration.mutate(scenario), level + 1);
      }
    }
  }

  /**
   * An aggregation of an ordering with a list (of size > 1) that should prove to be in strictly
   * increasing order according to that ordering.
   */
  private static class Scenario<T extends @Nullable Object> {
    final Ordering<T> ordering;
    final List<T> strictlyOrderedList;

    assertEquals("bar", Iterables.getLast(iterable, "qux"));
  }

  /**
   * {@link ArrayList} extension that forbids the use of {@link Collection#iterator} for tests that
   * need to prove that it isn't called.
   */
  private static class DiesOnIteratorArrayList extends ArrayList<String> {
    /** @throws UnsupportedOperationException all the time */
    @Override
    public Iterator<String> iterator() {

    assertEquals("bar", Iterables.getLast(iterable, "qux"));
  }

  /**
   * {@link ArrayList} extension that forbids the use of {@link Collection#iterator} for tests that
   * need to prove that it isn't called.
   */
  private static class DiesOnIteratorArrayList extends ArrayList<String> {
    /** @throws UnsupportedOperationException all the time */
    @Override
    public Iterator<String> iterator() {

    }
  }

  /*
   * Preconditions.checkNotNull is *intended* for performing eager null checks on parameters that a
   * nullness checker can already "prove" are non-null. That means that the first parameter to
   * checkNotNull *should* be annotated to require it to be non-null.
   *
   * However, for a variety of reasons, Google developers have written a ton of code over the past

    public int hashCode() {
      // Warning: this is broken if size() == 0, so it is critical that we
      // substitute an empty ImmutableSet to the user in place of this

      // It's a weird formula, but tests prove it works.
      int adjust = size() - 1;
      for (int i = 0; i < axes.size(); i++) {
        adjust *= 31;
        adjust = ~~adjust;
        // in GWT, we have to deal with integer overflow carefully
      }

*  particular purpose or non-infringing. The entire risk as to the     *
*  quality and performance of the Covered Software is with You.        *
*  Should any Covered Software prove defective in any respect, You     *
*  (not any Contributor) assume the cost of any necessary servicing,   *
*  repair, or correction. This disclaimer of warranty constitutes an   *