```

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)
```

将会校验数据，在数据无效时展示清晰的错误信息，并在 OpenAPI 模式的*路径操作*中记录该参​​数。

// RUN: tf-mlir-translate -mlir-tf-mlir-to-str-attr -mlir-print-local-scope %s | FileCheck %s

module attributes {tf.versions = {producer = 888 : i32}} {
  func.func @main(%arg0: tensor<?xi32>) -> tensor<?xi32> {
    %0 = "tf.Identity"(%arg0) : (tensor<?xi32>) -> tensor<?xi32> loc(unknown)
    func.return %0 : tensor<?xi32> loc(unknown)
  } loc(unknown)
} loc(unknown)

const pathBase = 1000

// Path returns a tile coordinate path describing t.
func (t Tile) Path() string {
	n := t.N
	nStr := fmt.Sprintf("%03d", n%pathBase)
	for n >= pathBase {
		n /= pathBase
		nStr = fmt.Sprintf("x%03d/%s", n%pathBase, nStr)
	}
	pStr := ""
	if t.W != 1<<uint(t.H) {
		pStr = fmt.Sprintf(".p/%d", t.W)
	}
	var L string
	if t.L == -1 {
		L = "data"
	} else {
		L = fmt.Sprintf("%d", t.L)

    TearDownTestCaseFunc tear_down_tc,
    TestFactoryBase* factory);

// If *pstr starts with the given prefix, modifies *pstr to be right
// past the prefix and returns true; otherwise leaves *pstr unchanged
// and returns false.  None of pstr, *pstr, and prefix can be NULL.
GTEST_API_ bool SkipPrefix(const char* prefix, const char** pstr);

#if GTEST_HAS_TYPED_TEST || GTEST_HAS_TYPED_TEST_P

		BPtr:         &zBool,
		Bs:           []bool{zBool},
		BPtrs:        []*bool{&zBool},
		Bytes:        []byte{},
		BytesPtr:     &zBytes,
		SPtr:         &zStr,
		Ss:           []string{zStr},
		SPtrs:        []*string{&zStr},
		Children:     []Child{{}},
		ChildPtr:     new(Child),
		ChildToEmbed: ChildToEmbed{},
	}
	if !reflect.DeepEqual(v, want) {

// RUN: tf-mlir-translate -mlir-tf-str-attr-to-mlir %s -mlir-print-debuginfo -mlir-print-local-scope | FileCheck %s

"\0A\0Amodule attributes {tf.versions = {producer = 888 : i32}} {\0A func.func @main(%arg0: tensor<?xi32>) -> tensor<?xi32> {\0A %0 = \22tf.Identity\22(%arg0) : (tensor<?xi32>) -> tensor<?xi32> loc(unknown)\0A return %0 : tensor<?xi32> loc(unknown)\0A } loc(unknown)\0A} loc(unknown)"

// Test simple serialized computation consisting of a function named `main`

    TearDownTestCaseFunc tear_down_tc,
    TestFactoryBase* factory);

// If *pstr starts with the given prefix, modifies *pstr to be right
// past the prefix and returns true; otherwise leaves *pstr unchanged
// and returns false.  None of pstr, *pstr, and prefix can be NULL.
GTEST_API_ bool SkipPrefix(const char* prefix, const char** pstr);

#if GTEST_HAS_TYPED_TEST || GTEST_HAS_TYPED_TEST_P

			if res != tt.want {
				t.Errorf("got %v, want: %v", res, tt.want)
			}
		})
	}
}

func TestK8sObject_ResolveK8sConflict(t *testing.T) {
	getK8sObject := func(ystr string) *K8sObject {
		o, err := ParseYAMLToK8sObject([]byte(ystr))
		if err != nil {
			panic(err)
		}
		// Ensure that json data is in sync.
		// Since the object was created using yaml, json is empty.

  Message& operator <<(const ::std::wstring& wstr);
#endif  // GTEST_HAS_STD_WSTRING

#if GTEST_HAS_GLOBAL_WSTRING
  // Converts the given wide string to a narrow string using the UTF-8
  // encoding, and streams the result to this Message object.
  Message& operator <<(const ::wstring& wstr);
#endif  // GTEST_HAS_GLOBAL_WSTRING

	Frsize   uint64
	Blocks   uint64
	Bfree    uint64
	Bavail   uint64
	Files    uint64
	Ffree    uint64
	Favail   uint64
	Fsid     uint64
	Basetype [16]int8
	Flag     uint64
	Namemax  uint64
	Fstr     [32]int8
}

type RawSockaddrInet4 struct {
	Family uint16
	Port   uint16
	Addr   [4]byte /* in_addr */
	Zero   [8]int8
}

type RawSockaddrInet6 struct {
	Family   uint16