Por ejemplo, podrías tener un archivo `main.py` con:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip | Consejo

El segundo argumento de <a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> es el valor por defecto a retornar.

			bootLogIf(GlobalContext, err, logger.ErrorKind)
		}
	}
	secureConn = true

	// Certs might be symlinks, reload them every 10 seconds.
	manager.UpdateReloadDuration(10 * time.Second)

	// syscall.SIGHUP to reload the certs.
	manager.ReloadOnSignal(syscall.SIGHUP)

	return x509Certs, manager, secureConn, nil
}

	return nil
}

const siteHealTimeInterval = 30 * time.Second

func (c *SiteReplicationSys) startHealRoutine(ctx context.Context, objAPI ObjectLayer) {
	ctx, cancel := globalLeaderLock.GetLock(ctx)
	defer cancel()

	healTimer := time.NewTimer(siteHealTimeInterval)
	defer healTimer.Stop()

	var maxRefreshDurationSecondsForLog float64 = 10 // 10 seconds..

	for {
		select {
		case <-healTimer.C:

            assertTrue("Should find custom thread in dump", customThreadFound.get() > 0);

        } finally {
            latch.countDown();
            customThread.join(1000); // Wait up to 1 second for thread to finish
        }
    }

    public void test_writeThreadDump_fileContent() throws IOException {
        Path tempFile = Files.createTempFile("test-thread-dump-content", ".txt");

        try {

        // Test zero boundary
        testBoundaryValue(0L);

        // Test one millisecond boundaries
        testBoundaryValue(1L);
        testBoundaryValue(-1L);

        // Test one second boundaries
        testBoundaryValue(1000L);
        testBoundaryValue(-1000L);

        // Test one minute boundaries
        testBoundaryValue(60000L);
        testBoundaryValue(-60000L);

        response.readParametersWireFormat(buffer1, 0, 6);
        assertEquals(100, response.getAvailable());
        assertEquals(TransPeekNamedPipeResponse.STATUS_CONNECTION_OK, response.getStatus());

        // Second read - should update values
        byte[] buffer2 = new byte[10];
        SMBUtil.writeInt2(500, buffer2, 0);
        SMBUtil.writeInt2(0, buffer2, 2);

        assertSame(d, r1, "nextElement should return the same instance");
        // After first call isPrimary should be false
        assertFalse(d.getIsPrimary(), "isPrimary should be cleared after first call");
        // Second call keeps the same state
        SmbComTransactionResponse r2 = (SmbComTransactionResponse) d.nextElement();
        assertSame(d, r2, "Subsequent calls still return same instance");

     *
     * @param name the circuit breaker name
     */
    public SimpleCircuitBreaker(String name) {
        this(name, 5, 3, 30000L); // 5 failures, 3 successes, 30 second timeout
    }

    /**
     * Creates a simple circuit breaker
     *
     * @param name the circuit breaker name
     * @param failureThreshold number of consecutive failures to open circuit

                assertEquals(result, crawlingInfoHelper.generateId(dataMap));
                counter.incrementAndGet();
            });
        }
        pool.shutdown();
        pool.awaitTermination(10, TimeUnit.SECONDS);
        assertEquals(1000, counter.get());
    }

    public void test_getCanonicalSessionId() {
        assertEquals("session123", crawlingInfoHelper.getCanonicalSessionId("session123"));

Cela va valider les données, montrer une erreur claire si ces dernières ne sont pas valides, et documenter le paramètre dans le schéma `OpenAPI` de cette *path operation*.

## Rajouter plus de validation

Vous pouvez aussi rajouter un second paramètre `min_length` :

{* ../../docs_src/query_params_str_validations/tutorial003.py hl[9] *}

## Ajouter des validations par expressions régulières