}
  }

  /**
   * Returns the set of all possible subsets of {@code set}. For example, {@code
   * powerSet(ImmutableSet.of(1, 2))} returns the set {@code {{}, {1}, {2}, {1, 2}}}.
   *
   * <p>Elements appear in these subsets in the same iteration order as they appeared in the input
   * set. The order in which these subsets appear in the outer set is undefined. Note that the power

    }
  }

  /**
   * Returns the set of all possible subsets of {@code set}. For example, {@code
   * powerSet(ImmutableSet.of(1, 2))} returns the set {@code {{}, {1}, {2}, {1, 2}}}.
   *
   * <p>Elements appear in these subsets in the same iteration order as they appeared in the input
   * set. The order in which these subsets appear in the outer set is undefined. Note that the power

  }

  /** Identifies just tryEnterXxx methods (a subset of {@link #isAnyEnter}), which never block. */
  private static boolean isTryEnter(Method method) {
    return method.getName().startsWith("tryEnter");
  }

  /**
   * Identifies just enterIfXxx methods (a subset of {@link #isAnyEnter}), which are mostly like the
   * enterXxx methods but behave like tryEnterXxx in some scenarios.

  }

  /** Identifies just tryEnterXxx methods (a subset of {@link #isAnyEnter}), which never block. */
  private static boolean isTryEnter(Method method) {
    return method.getName().startsWith("tryEnter");
  }

  /**
   * Identifies just enterIfXxx methods (a subset of {@link #isAnyEnter}), which are mostly like the
   * enterXxx methods but behave like tryEnterXxx in some scenarios.

    Building signatures from these allows TF Serving to honor requests using the
    different APIs (Classify, Regress, and Predict). Furthermore,
    `serving_input_receiver_fn()` may now specify alternative subsets of nodes
    that may act as inputs. This allows, for instance, producing a prediction
    signature for a classifier that accepts raw `Tensors` instead of a
    serialized `tf.Example`.

    SortedSet<String> subset = elementSet.subSet("b", "f");
    assertThat(subset).containsExactly("b", "c", "d", "e").inOrder();

    assertTrue(subset.remove("c"));
    assertThat(elementSet).containsExactly("a", "b", "d", "e", "f").inOrder();
    assertThat(subset).containsExactly("b", "d", "e").inOrder();
    assertEquals(10, ms.size());

    assertFalse(subset.remove("a"));

    SortedSet<String> set = of("e");
    assertTrue(set.subSet("c", "g") instanceof ImmutableSortedSet);
    assertThat(set.subSet("c", "g")).contains("e");
    assertThat(set.subSet("e", "g")).contains("e");
    assertThat(set.subSet("f", "g")).isSameInstanceAs(this.<String>of());
    assertThat(set.subSet("c", "e")).isSameInstanceAs(this.<String>of());
    assertThat(set.subSet("c", "d")).isSameInstanceAs(this.<String>of());
  }

    SortedSet<String> set = of("e");
    assertTrue(set.subSet("c", "g") instanceof ImmutableSortedSet);
    assertThat(set.subSet("c", "g")).contains("e");
    assertThat(set.subSet("e", "g")).contains("e");
    assertThat(set.subSet("f", "g")).isSameInstanceAs(this.<String>of());
    assertThat(set.subSet("c", "e")).isSameInstanceAs(this.<String>of());
    assertThat(set.subSet("c", "d")).isSameInstanceAs(this.<String>of());
  }

  }

  @Override
  public NavigableSet<E> subSet(
      E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
    return new SafeTreeSet<>(
        delegate.subSet(
            checkValid(fromElement), fromInclusive, checkValid(toElement), toInclusive));
  }

  @Override
  public SortedSet<E> subSet(E fromElement, E toElement) {
    return subSet(fromElement, true, toElement, false);
  }

  }

  @Override
  public NavigableSet<E> subSet(
      E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
    return new SafeTreeSet<>(
        delegate.subSet(
            checkValid(fromElement), fromInclusive, checkValid(toElement), toInclusive));
  }

  @Override
  public SortedSet<E> subSet(E fromElement, E toElement) {
    return subSet(fromElement, true, toElement, false);
  }