We see that we are going to need some dependencies used in several places of the application.

So we put them in their own `dependencies` module (`app/dependencies.py`).

We will now use a simple dependency to read a custom `X-Token` header:

//// tab | Python 3.9+

```Python hl_lines="3  6-8" title="app/dependencies.py"
{!> ../../docs_src/bigger_applications/app_an_py39/dependencies.py!}
```

////

//// tab | Python 3.8+

│   ├── main.py
│   └── test_main.py
```

➡️ 💬 👈 🔜 📁 `main.py` ⏮️ 👆 **FastAPI** 📱 ✔️ 🎏 **➡ 🛠️**.

⚫️ ✔️ `GET` 🛠️ 👈 💪 📨 ❌.

⚫️ ✔️ `POST` 🛠️ 👈 💪 📨 📚 ❌.

👯‍♂️ *➡ 🛠️* 🚚 `X-Token` 🎚.

//// tab | 🐍 3️⃣.6️⃣ & 🔛

```Python
{!> ../../docs_src/app_testing/app_b/main.py!}
```

////

//// tab | 🐍 3️⃣.1️⃣0️⃣ & 🔛

```Python

      with:
        title: Update the RBE images to the latest container versions
        committer: TensorFlow Release Automation <******@****.***>
        token: ${{ secrets.JENKINS_TOKEN }}
        reviewers: mihaimaruseac,learning-to-play,nitins17
        body: |

	}

	if subtle.ConstantTimeCompare([]byte(resp.Header.Get(xhttp.AmzRequestToken)), []byte(eventData.GetObjectContext.OutputToken)) != 1 {
		tokenErr := errorCodes.ToAPIErr(ErrInvalidToken)
		tokenErr.Description = "The request token included in the request is invalid"
		writeErrorResponse(ctx, w, tokenErr, r.URL)
		return
	}

	// Set all the relevant lambda forward headers if found.
	fwdHeadersToS3(resp.Header, w)

}

// UnmarshalXML - decodes XML data.
func (f *Filter) UnmarshalXML(d *xml.Decoder, start xml.StartElement) (err error) {
	f.set = true
	for {
		// Read tokens from the XML document in a stream.
		t, err := d.Token()
		if err != nil {
			if err == io.EOF {
				break
			}
			return err
		}

		if se, ok := t.(xml.StartElement); ok {
			switch se.Name.Local {
			case "Prefix":
				var p Prefix

*경로 작동 데코레이터*에서 `dependencies`를 사용하면 편집기/도구 오류를 피하며 실행되도록 할 수 있습니다.

또한 코드에서 사용되지 않는 매개변수를 보고 불필요하다고 생각할 수 있는 새로운 개발자의 혼란을 방지하는데 도움이 될 수 있습니다.

///

/// info | "정보"

이 예시에서 `X-Key`와 `X-Token`이라는 커스텀 헤더를 만들어 사용했습니다.

그러나 실제로 보안을 구현할 때는 통합된 [보안 유틸리티 (다음 챕터)](../security/index.md){.internal-link target=_blank}를 사용하는 것이 더 많은 이점을 얻을 수 있습니다.

///

## 의존성 오류와 값 반환하기

평소에 사용하던대로 같은 의존성 *함수*를 사용할 수 있습니다.

It has a `GET` operation that could return an error.

It has a `POST` operation that could return several errors.

Both *path operations* require an `X-Token` header.

//// tab | Python 3.10+

```Python
{!> ../../docs_src/app_testing/app_b_an_py310/main.py!}
```

////

//// tab | Python 3.9+

```Python

{\n  @if $enable-rounded {\n    border-bottom-left-radius: $radius;\n  }\n}\n","// Inline code\ncode {\n  @include font-size($code-font-size);\n  color: $code-color;\n  word-wrap: break-word;\n\n  // Streamline the style when inside anchors to avoid broken underline and more\n  a > & {\n    color: inherit;\n  }\n}\n\n// User input typically entered via keyboard\nkbd {\n  padding: $kbd-padding-y $kbd-padding-x;\n  @include font-size($kbd-font-size);\n  color: $kbd-color;\n  background-color: $kbd-bg;\n...

supported.languages=ar,bg,bn,ca,ckb_IQ,cs,da,de,el,en_IE,en,es,et,eu,fa,fi,fr,gl,gu,he,hi,hr,hu,hy,id,it,ja,ko,lt,lv,mk,ml,nl,no,pa,pl,pt_BR,pt,ro,ru,si,sq,sv,ta,te,th,tl,tr,uk,ur,vi,zh_CN,zh_TW,zh
api.access.token.length=60
api.access.token.required=false
api.access.token.request.parameter=
api.admin.access.permissions=Radmin-api
api.search.accept.referers=
api.search.scroll=false
api.json.response.headers=
api.json.response.exception.included=false

	}

	req, err := http.NewRequest(http.MethodPost, target.args.Endpoint.String(), bytes.NewReader(data))
	if err != nil {
		return nil, err
	}

	// Verify if the authToken already contains
	// <Key> <Token> like format, if this is
	// already present we can blindly use the
	// authToken as is instead of adding 'Bearer'
	tokens := strings.Fields(target.args.AuthToken)
	switch len(tokens) {
	case 2: