if _, err := uuid.Parse(vid); err != nil {
			return opts, InvalidVersionID{
				Bucket:    bucket,
				Object:    object,
				VersionID: vid,
			}
		}
	}

	// default case of passing encryption headers to backend
	opts, err = getDefaultOpts(r.Header, false, nil)
	if err != nil {
		return opts, err
	}
	opts.PartNumber = partNumber
	opts.VersionID = vid

```

由于我们必须用 `Query(default=None)` 替换默认值 `None`，`Query` 的第一个参数同样也是用于定义默认值。

所以：

```Python
q: Union[str, None] = Query(default=None)
```

...使得参数可选，等同于：

```Python
q: str = None
```

但是 `Query` 显式地将其声明为查询参数。

然后，我们可以将更多的参数传递给 `Query`。在本例中，适用于字符串的 `max_length` 参数：

```Python
q: Union[str, None] = Query(default=None, max_length=50)
```

     *             installation has failed.
     * @throws IllegalArgumentException in case of parameter {@code session} is {@code null} or
     *          {@code artifact} is {@code null}.
     */
    default void install(Session session, ProducedArtifact artifact) {
        install(session, Collections.singletonList(artifact));
    }

    /**
     * @param session the repository session

                  server_def, tensorflow::Env::Default(), &worker_server1)
                  .ok());
  ASSERT_TRUE(worker_server1->Start().ok());

  server_def.set_task_index(2);
  std::unique_ptr<tensorflow::GrpcServer> worker_server2;
  ASSERT_TRUE(tensorflow::GrpcServer::Create(
                  server_def, tensorflow::Env::Default(), &worker_server2)
                  .ok());

$(TARGET_OUT):
	@mkdir -p $@

# If the hub is not explicitly set, use default to istio.
HUB ?=istio
ifeq ($(HUB),)
  $(error "HUB cannot be empty")
endif

# For dockerx builds, allow HUBS which is a space separated list of hubs. Default to HUB.
HUBS ?= $(HUB)

# If tag not explicitly set in users' .istiorc.mk or command line, default to the git sha.
TAG ?= $(shell git rev-parse --verify HEAD)
ifeq ($(TAG),)

			if err != nil {
				err = msgp.WrapError(err, "Count")
				return
			}
		case "Bytes":
			z.Bytes, err = dc.ReadInt64()
			if err != nil {
				err = msgp.WrapError(err, "Bytes")
				return
			}
		default:
			err = dc.Skip()
			if err != nil {
				err = msgp.WrapError(err)
				return
			}
		}
	}
	return
}

// EncodeMsg implements msgp.Encodable
func (z RStat) EncodeMsg(en *msgp.Writer) (err error) {

		default:
			p.errorf("bad int size for DATA argument: %d", sz)
		}
	case obj.TYPE_FCONST:
		switch sz {
		case 4:
			nameAddr.Sym.WriteFloat32(p.ctxt, nameAddr.Offset, float32(valueAddr.Val.(float64)))
		case 8:
			nameAddr.Sym.WriteFloat64(p.ctxt, nameAddr.Offset, valueAddr.Val.(float64))
		default:
			p.errorf("bad float size for DATA argument: %d", sz)
		}

                    return 1;
                case COMBINATION_ITEM:
                    return 1; // 1.1 > 1-sp

                case LIST_ITEM:
                    return 1; // 1.1 > 1-1

                default:
                    throw new IllegalStateException("invalid item: " + item.getClass());
            }
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) {

	case syscall.O_WRONLY | syscall.O_CREAT | syscall.O_APPEND:
		access = syscall.FILE_APPEND_DATA
	default:
		return nil, fmt.Errorf("Unsupported flag (%d)", flag)
	}

	var createflag uint32
	switch {
	case flag&syscall.O_CREAT == syscall.O_CREAT:
		createflag = syscall.OPEN_ALWAYS
	default:
		createflag = syscall.OPEN_EXISTING
	}

     * If not set, System.in will be used by default.
     *
     * @return the input stream, or null if not set
     */
    @Nullable
    InputStream in();

    /**
     * Returns the output stream to be used for the Maven execution.
     * If not set, System.out will be used by default.
     *
     * @return the output stream, or null if not set
     */
    @Nullable