message);
                        }
                    } else {
                        done = true;
                    }
                } else {
                    done = true;
                }
            }
        } while (!done);

        ProjectRelocation rel = new ProjectRelocation();
        rel.project = project;
        rel.pomArtifact = pomArtifact;

				t.Errorf("#%d: %q: expected error %q; got none", i, test.input, test.error)
			}
			continue
		}
		if !strings.Contains(err.Error(), test.error) {
			t.Errorf("#%d: expected error %q; got %q", i, test.error, err)
			continue
		}
	}
}

func runBadTest(i int, test badExprTest, t *testing.T) (err error) {
	p := NewParser(nil, nil, nil) // Expression evaluation uses none of these fields of the parser.

		wg.Add(1)
		go func(ctx context.Context, peerChannel <-chan MetricV2, wg *sync.WaitGroup) {
			defer wg.Done()
			for {
				select {
				case m, ok := <-peerChannel:
					if !ok {
						return
					}
					select {
					case ch <- m:
					case <-ctx.Done():
						return
					}
				case <-ctx.Done():
					return
				}
			}
		}(ctx, peerChannels[index], &wg)
	}

// the token is the last token.
//
// The value is useful to stop processing early or when it is necessary to
// deliver a final empty token (which is different from a nil token).
// One could achieve the same behavior with a custom error value but
// providing one here is tidier.
// See the emptyFinalToken example for a use of this value.
var ErrFinalToken = errors.New("final token")

`Optional[Something]` là một cách viết ngắn gọn của `Union[Something, None]`, chúng là tương đương nhau.

Điều này cũng có nghĩa là trong Python 3.10, bạn có thể sử dụng `Something | None`:

//// tab | Python 3.10+

```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial009_py310.py!}
```

The way to describe this in OpenAPI, is to mark that field as **required**, because it will always be there.

Because of that, the JSON Schema for a model can be different depending on if it's used for **input or output**:

* for **input** the `description` will **not be required**
* for **output** it will be **required** (and possibly `None`, or in JSON terms, `null`)

OpenAPIスキーマを完全に無効にする場合は、`openapi_url=None` を設定できます。これにより、それを使用するドキュメントUIも無効になります。

## ドキュメントのURL

以下の2つのドキュメントUIを構築できます:

* **Swagger UI**: `/docs` で提供されます。
     * URL はパラメータ `docs_url` で設定できます。
     * `docs_url=None` を設定することで無効にできます。
* ReDoc: `/redoc` で提供されます。
     * URL はパラメータ `redoc_url` で設定できます。
     * `redoc_url=None` を設定することで無効にできます。

     * oldFuture is the previous task's newFuture.
     * outputFuture is the future we return to the caller, a nonCancellationPropagating taskFuture.
     *
     * newFuture is guaranteed to only complete once all tasks previously submitted to this instance
     * have completed - namely after oldFuture is done, and taskFuture has either completed or been

Tu modelo de response podría tener valores por defecto, como:

{* ../../docs_src/response_model/tutorial004_py310.py hl[9,11:12] *}

* `description: Union[str, None] = None` (o `str | None = None` en Python 3.10) tiene un valor por defecto de `None`.
* `tax: float = 10.5` tiene un valor por defecto de `10.5`.
* `tags: List[str] = []` tiene un valor por defecto de una lista vacía: `[]`.

    do {
      System.runFinalization();
      if (predicate.isDone()) {
        return;
      }
      CountDownLatch done = new CountDownLatch(1);
      createUnreachableLatchFinalizer(done);
      await(done);
      if (predicate.isDone()) {
        return;
      }
    } while (System.nanoTime() - deadline < 0);
    throw formatRuntimeException(