`Optional[Something]` насправді є скороченням для `Union[Something, None]`, вони еквівалентні.

Це також означає, що в Python 3.10 ви можете використовувати `Something | None`:

//// tab | Python 3.8 і вище

```Python hl_lines="1  4"
{!> ../../docs_src/python_types/tutorial009.py!}
```

// the DaemonSet and StatefulSet controllers for update and rollback, this object is beta. However,
// it may be subject to name and representation changes in future releases, and clients should not
// depend on its stability. It is primarily for internal use by controllers.
message ControllerRevision {
  // Standard object's metadata.

     *          {@link LongMathTest#testSqrtOfPerfectSquareAsDoubleIsPerfect}
     */
    long guess = (long) Math.sqrt((double) x);
    // Note: guess is always <= FLOOR_SQRT_MAX_LONG.
    long guessSquared = guess * guess;
    // Note (2013-2-26): benchmarks indicate that, inscrutably enough, using if statements is
    // faster here than using lessThanBranchFree.
    switch (mode) {
      case UNNECESSARY:

				if !contextCanceled(ctx) {
					healingLogIf(ctx, ctx.Err())
				}
				return false
			case results <- result:
				bgSeq.countScanned(madmin.HealItemObject)
				return true
			}
		}

		// Note: updates from healEntry to tracker must be sent on results channel.
		healEntry := func(bucket string, entry metaCacheEntry) {
			defer jt.Give()

			if entry.name == "" && len(entry.metadata) == 0 {

| `minio_system_memory_used`       | Used memory on the node. <br><br>Type: gauge            | `server` |
| `minio_system_memory_used_perc`  | Used memory percentage on the node. <br><br>Type: gauge | `server` |
| `minio_system_memory_free`       | Free memory on the node. <br><br>Type: gauge            | `server` |
| `minio_system_memory_total`      | Total memory on the node. <br><br>Type: gauge           | `server` |

  }

  // Test suppression

  private final Set<Method> suppressedTests = new HashSet<>();

  /**
   * Prevents the given methods from being run as part of the test suite.
   *
   * <p>Note: in principle this should never need to be used, but it might be useful if the
   * semantics of an implementation disagree in unforeseen ways with the semantics expected by a

     * is evicted due to the cache's eviction strategy, and not as a result of manual {@linkplain
     * Cache#invalidate invalidations}.
     */
    void recordEviction();

    /**
     * Returns a snapshot of this counter's values. Note that this may be an inconsistent view, as
     * it may be interleaved with update operations.
     */
    CacheStats snapshot();

  // Queues

  /**
   * A custom queue for managing eviction order. Note that this is tightly integrated with {@code
   * ReferenceEntry}, upon which it relies to perform its linking.
   *
   * <p>Note that this entire implementation makes the assumption that all elements which are in the
   * map are also in this queue, and that all elements not in the queue are not in the map.
   *

      return this;
    }

    /** Adds a key-value mapping to the built multimap if it is not already present. */
    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> put(K key, V value) {
      super.put(key, value);
      return this;
    }

    /**
     * Adds an entry to the built multimap if it is not already present.
     *
     * @since 11.0
     */
    @CanIgnoreReturnValue

  // If not set, use the default values:
  // - For scale up: 0 (i.e. no stabilization is done).
  // - For scale down: 300 (i.e. the stabilization window is 300 seconds long).
  // +optional
  optional int32 stabilizationWindowSeconds = 3;

  // selectPolicy is used to specify which policy should be used.
  // If not set, the default value Max is used.
  // +optional