```java
class MetricsEventListener extends EventListener {
  private static final Factory FACTORY = new Factory() {
    @Override public EventListener create(Call call) {
      if (Math.random() < 0.10) {
        return new MetricsEventListener(call);
      } else {
        return EventListener.NONE;
      }
    }
  };

  ...

labels.crawler_title_edit=General Config
labels.schedule=Schedule
labels.enabled=Enabled
labels.day_for_cleanup=Delete old documents
labels.day=days
labels.crawl_button_update=Update
labels.none=None
labels.crawling_thread_count=Concurrent Crawler Config
labels.incremental_crawling=Check Last Modified
labels.search_log_enabled=Search Log
labels.user_info_enabled=User Log
labels.user_favorite_enabled=Favorite Log

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

### 📁

🔜 🎏 🏗 📁 ✍ 📁 `Dockerfile` ⏮️:

```{ .dockerfile .annotate }
# (1)
FROM python:3.9

# (2)
WORKDIR /code

        try {
            final XPathNodes list = getXPathAPI().selectNodeList(document, "//BASE");
            if (list.size() > 0) {
                final Node node = list.get(0);
                final Node attrNode = node.getAttributes().getNamedItem("href");
                if (attrNode != null) {
                    String attrValue = attrNode.getNodeValue();

예를 들어, `title` 메타데이터 값을 경로 매개변수 `item_id`에 선언하려면 다음과 같이 입력할 수 있습니다:

{* ../../docs_src/path_params_numeric_validations/tutorial001.py hl[10] *}

/// note | 참고

경로 매개변수는 경로의 일부여야 하므로 언제나 필수적입니다.

즉, `...`로 선언해서 필수임을 나타내는게 좋습니다.

그럼에도 `None`으로 선언하거나 기본값을 지정할지라도 아무 영향을 끼치지 않으며 언제나 필수입니다.

///

## 필요한 경우 매개변수 정렬하기

`str` 형인 쿼리 매개변수 `q`를 필수로 선언하고 싶다고 해봅시다.

  }

  /**
   * Invoked when a response fails to be read.
   *
   * Note that response failures do not necessarily fail the entire call.
   *
   * Starting with OkHttp 4.3 this may be invoked without a prior call to [responseHeadersStart]
   * or [responseBodyStart]. In earlier releases this method was documented to only be invoked after
   * one of those methods.
   */
  open fun responseFailed(
    call: Call,

t=/firefox/i.test(f());if(/Trident/i.test(f())&&r(e)&&"fixed"===m(e).position)return null;var n=b(e);for(o(n)&&(n=n.host);r(n)&&["html","body"].indexOf(l(n))<0;){var i=m(n);if("none"!==i.transform||"none"!==i.perspective||"paint"===i.contain||-1!==["transform","perspective"].indexOf(i.willChange)||t&&"filter"===i.willChange||t&&i.filter&&"none"!==i.filter)return n;n=n.parentNode}return null}(e)||n}var D="top",A="bottom",L="right",P="left",M="auto",k=[D,A,L,P],W="start",B="end",H="viewport",T="popper",R=k.r...

	// a single client certificate. Otherwise, the certificate to
	// policy mapping would be ambiguous.
	// However, we can filter all CA certificates and only check
	// whether they client has sent exactly one (non-CA) leaf certificate.
	const MaxIntermediateCAs = 10
	var (
		peerCertificates = make([]*x509.Certificate, 0, len(r.TLS.PeerCertificates))
		intermediates    *x509.CertPool
		numIntermediates int
	)

                    return elements[index];
                  }
                };
              }
            })
        .named("AbstractList")
        .withFeatures(
            CollectionFeature.NONE, CollectionFeature.ALLOWS_NULL_VALUES, CollectionSize.ANY)
        .suppressing(suppressForAbstractList())
        .createTestSuite();
  }

  public Test testsForAbstractSequentialList() {

{* ../../docs_src/path_params_numeric_validations/tutorial001_an_py310.py hl[10] *}

/// note | Nota

Un parámetro de path siempre es requerido ya que tiene que formar parte del path. Incluso si lo declaras con `None` o le asignas un valor por defecto, no afectará en nada, siempre será requerido.

///

## Ordena los parámetros como necesites

/// tip | Consejo