### Use cases: external service { #use-cases-external-service }

An example could be that you have an external authentication provider that you need to call.

You send it a token and it returns an authenticated user.

import os

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

/// tip

Het tweede argument van <a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> is de standaardwaarde die wordt geretourneerd.

Als je dit niet meegeeft, is de standaardwaarde `None`. In dit geval gebruiken we standaard `"World"`.

///

            throw new FessSystemException("Could not find extractorFactory.");
        }
        Extractor extractor = extractorFactory.getExtractor(responseData.getMimeType());
        if (extractor == null) {
            extractor = ComponentUtil.getComponent("tikaExtractor");
            if (extractor == null) {
                throw new FessSystemException("Could not find tikaExtractor.");
            }
        }

```Python hl_lines="3"
import os

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

/// tip

<a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> এর দ্বিতীয় আর্গুমেন্টটি হলো এর ডিফল্ট ভ্যালু যা রিটার্ন করা হবে।

যদি এটি দেওয়া না হয়, ডিফল্টভাবে `None` ব্যবহৃত হবে, এখানে আমরা ডিফল্ট ভ্যালু হিসেবে `"World"` ব্যবহার করেছি।

///

```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.

Si no se proporciona, es `None` por defecto; aquí proporcionamos `"World"` como el valor por defecto para usar.

///

                        logger.warn("Could not close a process input stream.", e);
                    }
                });
                CommonPoolUtil.execute(() -> {
                    try {
                        CloseableUtil.closeQuietly(p.getErrorStream());
                    } catch (final Exception e) {
                        logger.warn("Could not close a process error stream.", e);
                    }

            return parse(new GZIPInputStream(bis), false);
        } catch (final CrawlingAccessException e) {
            throw e;
        } catch (final Exception e) {
            throw new CrawlingAccessException("Could not parse Sitemaps: " + preloadDate, e);
        }
    }

    /**
     * Parses a text-based sitemap from the given input stream.
     * @param in the input stream to parse
     * @return the parsed sitemap set

  }

  @Override public void onOpen(WebSocket webSocket, Response response) {
    webSocket.send("Hello...");
    webSocket.send("...World!");
    webSocket.send(ByteString.decodeHex("deadbeef"));
    webSocket.close(1000, "Goodbye, World!");
  }

  @Override public void onMessage(WebSocket webSocket, String text) {
    System.out.println("MESSAGE: " + text);
  }

```txt
Hello, World from Flask!
```

Eğer <a href="http://localhost:8000/v2/" class="external-link" target="_blank">http://localhost:8000/v2/</a> adresine giderseniz, FastAPI'dan gelen yanıtı göreceksiniz:

```JSON
{
    "message": "Hello World"
}

     * @param scope the {link PathScope} to collect dependencies, must not be {@code null}
     * @return the collection result, never {@code null}
     * @throws DependencyResolverException if the dependency tree could not be built
     * @throws IllegalArgumentException if an argument is null or invalid
     * @see #collect(DependencyResolverRequest)
     */
    @Nonnull
    default DependencyResolverResult collect(