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

Wenn Sie `Optional[str]` anstelle von nur `str` verwenden, wird Ihr Editor Ihnen dabei helfen, Fehler zu erkennen, bei denen Sie annehmen könnten, dass ein Wert immer eine String (`str`) ist, obwohl er auch `None` sein könnte.

`Optional[Something]` ist tatsächlich eine Abkürzung für `Union[Something, None]`, diese beiden sind äquivalent.

// problematic types such as pointers. Note that it only does special handling
// for the troublesome types used in the test cases; it is not a general
// printer.
func sprintKey(key reflect.Value) string {
	switch str := key.Type().String(); str {
	case "*int":
		ptr := key.Interface().(*int)
		for i := range ints {
			if ptr == &ints[i] {
				return fmt.Sprintf("PTR%d", i)
			}
		}
		return "PTR???"
	case "unsafe.Pointer":

        return new AbstractIterator<E>() {
          final Iterator<? extends E> itr1 = set1.iterator();
          final Iterator<? extends E> itr2 = set2.iterator();

          @Override
          @CheckForNull
          protected E computeNext() {
            if (itr1.hasNext()) {
              return itr1.next();
            }
            while (itr2.hasNext()) {
              E e = itr2.next();

        return new AbstractIterator<E>() {
          final Iterator<? extends E> itr1 = set1.iterator();
          final Iterator<? extends E> itr2 = set2.iterator();

          @Override
          @CheckForNull
          protected E computeNext() {
            if (itr1.hasNext()) {
              return itr1.next();
            }
            while (itr2.hasNext()) {
              E e = itr2.next();

		}
	})

	if len(deepkeys) < 1 {
		return nil
	}

	deepConfig := buildNestedMap(deepkeys)
	strb, err := yaml.Marshal(deepConfig)
	if err != nil {
		return err
	}
	str := string(strb)

	g.emit("<p/>Accepts deep config files, like:")
	g.emit("<pre class=\"language-yaml\"><code>", str)
	g.emit("</code></pre>")
	return nil
}

func dereferenceMap(m map[string]string) (result map[string]string) {

    // CHECK: %[[mul2:.*]] = mhlo.multiply %arg2, %[[scr1]] : tensor<8xf32>
    // CHECK: %[[bcast_mul2:.+]] = "mhlo.dynamic_broadcast_in_dim"(%[[mul2]], {{.*}}) <{broadcast_dimensions = dense<3> : tensor<1xi64>}> : (tensor<8xf32>, tensor<4xindex>) -> tensor<8x8x8x8xf32>
    // CHECK: %[[mul3:.*]] = mhlo.multiply %[[grad]], %[[bcast_mul2]] : tensor<8x8x8x8xf32>

    // CHECK: %[[scale_backprop:.*]] = mhlo.multiply %[[scr1]], %[[scr2]] : tensor<8xf32>

	SSUBW2:    "SSUBW2",
	ST1:       "ST1",
	ST2:       "ST2",
	ST3:       "ST3",
	ST4:       "ST4",
	STLR:      "STLR",
	STLRB:     "STLRB",
	STLRH:     "STLRH",
	STLXP:     "STLXP",
	STLXR:     "STLXR",
	STLXRB:    "STLXRB",
	STLXRH:    "STLXRH",
	STNP:      "STNP",
	STP:       "STP",
	STR:       "STR",
	STRB:      "STRB",
	STRH:      "STRH",
	STTR:      "STTR",
	STTRB:     "STTRB",

		}
		if s.Addr == 0 || s.Size == 0 {
			continue
		}
		secs = append(secs, s)
	}

	secOverlaps := func(s1, s2 *elf.Section) bool {
		st1 := s1.Addr
		st2 := s2.Addr
		en1 := s1.Addr + s1.Size
		en2 := s2.Addr + s2.Size
		return max(st1, st2) < min(en1, en2)
	}

	// Sort by address
	sort.SliceStable(secs, func(i, j int) bool {
		return secs[i].Addr < secs[j].Addr
	})

	Bo bool `json:"bo,omitempty"`

	Ur uint `json:"ur"`
	Uo uint `json:"uo,omitempty"`

	Str struct{} `json:"str"`
	Sto struct{} `json:"sto,omitempty"`
}

func TestOmitEmpty(t *testing.T) {
	var want = `{
 "sr": "",
 "omitempty": 0,
 "slr": null,
 "mr": {},
 "fr": 0,
 "br": false,
 "ur": 0,
 "str": {},
 "sto": {}
}`
	var o Optionals
	o.Sw = "something"
	o.Mr = map[string]any{}

func (deviceInfoSet DevInfo) SetDeviceRegistryPropertyString(deviceInfoData *DevInfoData, property SPDRP, str string) error {
	str16, err := UTF16FromString(str)
	if err != nil {
		return err
	}
	err = SetupDiSetDeviceRegistryProperty(deviceInfoSet, deviceInfoData, property, utf16ToBuf(append(str16, 0)))
	runtime.KeepAlive(str16)
	return err
}