{!../../docs_src/python_types/tutorial009.py!}
```

Using `Optional[str]` instead of just `str` will let the editor help you detect errors where you could be assuming that a value is always a `str`, when it could actually be `None` too.

`Optional[Something]` is actually a shortcut for `Union[Something, None]`, they are equivalent.

This also means that in Python 3.10, you can use `Something | None`:

//// tab | Python 3.10+

```Python hl_lines="1"

    @ParameterizedTest(name = "encode({1}) -> {2}")
    @MethodSource("encodeProvider")
    void testEncode(byte[] input, String expected) {
        // Arrange & Act
        String actual = Base64.encode(input);
        // Assert
        assertEquals(expected, actual, "Base64.encode should match expected string");
    }

    /**
     * Data provider for Base64 strings and expected decoded byte arrays.
     */

        int expected = Byte.compare(x, y);
        int actual = SignedBytes.compare(x, y);
        if (expected == 0) {
          assertWithMessage(x + ", " + y).that(actual).isEqualTo(expected);
        } else if (expected < 0) {
          assertWithMessage(x + ", " + y + " (expected: " + expected + ", actual" + actual + ")")
              .that(actual < 0)
              .isTrue();
        } else {

	}
	CheckIndices(t, expectedIndices, indices)
}

func CheckIndices(t *testing.T, expected, actual []*schema.Index) {
	if len(expected) != len(actual) {
		t.Errorf("expected %d indices, but got %d", len(expected), len(actual))
		return
	}

	for i, ei := range expected {
		t.Run(ei.Name, func(t *testing.T) {
			ai := actual[i]
			tests.AssertObjEqual(t, ai, ei, "Name", "Class", "Type", "Where", "Comment", "Option")

        byte[] actual = NtlmUtil.getNTLMv2Response(key, server, clientChallenge, nanos1601, avPairs);

        // Assert
        assertArrayEquals(expected, actual, "Computed response must match manual construction");
        // Also verify client challenge sits at mac(16) + blob offset 16
        assertArrayEquals(clientChallenge, Arrays.copyOfRange(actual, 16 + 16, 16 + 16 + 8));
    }

    @Test

import org.mockito.Mock;
import org.mockito.junit.jupiter.MockitoExtension;

/**
 * Unit tests for the SmbFile class.
 * This class focuses on testing the logic of SmbFile without actual network communication,
 * using mocks where necessary.
 */
@ExtendWith(MockitoExtension.class)
public class SmbFileTest {

    @Mock
    private NtlmPasswordAuthentication mockAuth;

    @BeforeEach

    //                                                                        ============
    /**
     * Verifies that the CRUD mode matches the expected mode.
     *
     * @param crudMode the actual CRUD mode
     * @param expectedMode the expected CRUD mode
     */
    protected void verifyCrudMode(final int crudMode, final int expectedMode) {
        if (crudMode != expectedMode) {

    //                                                                        ============
    /**
     * Verifies that the CRUD mode matches the expected mode.
     *
     * @param crudMode the actual CRUD mode
     * @param expectedMode the expected CRUD mode
     */
    protected void verifyCrudMode(final int crudMode, final int expectedMode) {
        if (crudMode != expectedMode) {

 */
package okhttp3.internal.platform

import android.content.Context
import android.os.Build
import java.lang.IllegalStateException
import okhttp3.internal.platform.android.AndroidLog

actual object PlatformRegistry {
  actual fun findPlatform(): Platform {
    AndroidLog.enable()

    val androidPlatform =
      Android10Platform.buildIfSupported()
        ?: AndroidPlatform.buildIfSupported()

    void testKnownMapping() {
        final int dosErr = 0x00010001;
        final int expectedNt = 0xc0000002;
        Optional<Integer> actual = findNtStatus(dosErr);
        assertTrue(actual.isPresent(), String.format("Mapping for %08x should exist", dosErr));
        assertEquals(expectedNt, actual.get(), String.format("NTSTATUS for %08x should be %08x", dosErr, expectedNt));
    }

    @Test