nums.add(3);
    Predicate<Integer> isThree = Predicates.in(nums);
    assertFalse(isThree.apply(3));
  }

  /*
   * Tests that compilation will work when applying explicit types.
   */
  @SuppressWarnings("unused") // compilation test
  public void testIn_compilesWithExplicitSupertype() {
    Collection<Number> nums = ImmutableSet.of();
    Predicate<Number> p1 = Predicates.in(nums);

  @GwtIncompatible // SerializableTester
  public void testStringConverterSerialization() {
    SerializableTester.reserializeAndAssert(Doubles.stringConverter());
  }

  public void testToArray() {
    // need explicit type parameter to avoid javac warning!?
    List<Double> none = Arrays.<Double>asList();
    assertThat(Doubles.toArray(none)).isEqualTo(EMPTY);

    List<Double> one = Arrays.asList(1.0);

I think `Union[SomeType, None]` is more explicit about what it means.

It's just about the words and names. But those words can affect how you and your teammates think about the code.

As an example, let's take this function:

        return (logX2Floor < 2 * logFloor + 1) ? logFloor : logFloor + 1;
    }
    throw new AssertionError();
  }

  /*
   * The maximum number of bits in a square root for which we'll precompute an explicit half power
   * of two. This can be any value, but higher values incur more class load time and linearly
   * increasing memory consumption.
   */
  @VisibleForTesting static final int SQRT2_PRECOMPUTE_THRESHOLD = 256;

   * is empty.
   *
   * <p><b>Warning:</b> Typical uses of the resulting iterator may produce an infinite loop. You
   * should use an explicit {@code break} or be certain that you will eventually remove all the
   * elements.
   *
   * <p>To cycle over the iterable {@code n} times, use the following: {@code
   * Iterables.concat(Collections.nCopies(n, iterable))}

  @GwtIncompatible // SerializableTester
  public void testStringConverterSerialization() {
    SerializableTester.reserializeAndAssert(Ints.stringConverter());
  }

  public void testToArray() {
    // need explicit type parameter to avoid javac warning!?
    List<Integer> none = Arrays.<Integer>asList();
    assertThat(Ints.toArray(none)).isEqualTo(EMPTY);

    List<Integer> one = Arrays.asList((int) 1);

        // whether we are working on a transitive dependency or not. This
        // allows depMgmt to always override transitive dependencies, while
        // explicit child override depMgmt (viz. depMgmt should only
        // provide defaults to children, but should override transitives).
        // We can do this by calling isChildOfRootNode on the current node.

        } else if (createNewEntry || valueReference.isLoading()) {
          removeLoadingValue(key, hash, computingValueReference);
          return null;
        } else {
          removeEntry(e, hash, RemovalCause.EXPLICIT);
          return null;
        }
      } finally {
        unlock();
        postWriteCleanup();
      }
    }

   * user-created objects that aren't accessible via this range set's methods. This is generally
   * used to determine whether {@code copyOf} implementations should make an explicit copy to avoid
   * memory leaks.
   */
  boolean isPartialView() {
    return ranges.isPartialView();
  }

  /** Returns a new builder for an immutable range set. */

  /**
   * Returns true if the given member is a method that overrides {@link Object#equals(Object)}.
   *
   * <p>The documentation for {@link Object#equals} says it should accept null, so don't require an
   * explicit {@code @Nullable} annotation (see <a
   * href="https://github.com/google/guava/issues/1819">#1819</a>).
   *
   * <p>It is not necessary to consider visibility, return type, or type parameter declarations. The