{* ../../docs_src/events/tutorial003_py39.py hl[1,13] *}

A **context manager** in Python is something that you can use in a `with` statement, for example, `open()` can be used as a context manager:

```Python
with open("file.txt") as file:
    file.read()
```

In recent versions of Python, there's also an **async context manager**. You would use it with `async with`:

```Python
async with lifespan(app):
    await do_stuff()
```

Um **gerenciador de contexto** em Python é algo que você pode usar em uma declaração `with`, por exemplo, `open()` pode ser usado como um gerenciador de contexto:

```Python
with open("file.txt") as file:
    file.read()
```

Em versões mais recentes do Python, há também um **gerenciador de contexto assíncrono**. Você o usaria com `async with`:

```Python
async with lifespan(app):
    await do_stuff()

import okhttp3.Request

class SynchronousGet {
  private val client = OkHttpClient()

  fun run() {
    val request =
      Request
        .Builder()
        .url("https://publicobject.com/helloworld.txt")
        .build()

    client.newCall(request).execute().use { response ->
      if (!response.isSuccessful) throw IOException("Unexpected code $response")

      for ((name, value) in response.headers) {

# ==============================================================================
#
# setup.packages.sh: Given a list of Ubuntu packages, install them and clean up.
# Usage: setup.packages.sh <package_list.txt>
set -e

# Prevent apt install tzinfo from asking our location (assumes UTC)
export DEBIAN_FRONTEND=noninteractive

apt-get update
# Remove commented lines and blank lines

<div class="termy">

```console
$ uv pip install -r requirements.txt
---> 100%
```

</div>

////

/// details | 關於 `requirements.txt`

一個包含一些套件的 `requirements.txt` 檔案看起來應該是這樣的：

```requirements.txt
fastapi[standard]==0.113.0
pydantic==2.8.0
```

///

## 執行程式

在啟用虛擬環境後，你可以執行你的程式，它將使用虛擬環境中的 Python 和你在其中安裝的套件。

<div class="termy">

```console
$ uv pip install -r requirements.txt
---> 100%
```

</div>

////

/// details | 关于 `requirements.txt`

一个包含一些软件包的 `requirements.txt` 文件看起来应该是这样的：

```requirements.txt
fastapi[standard]==0.113.0
pydantic==2.8.0
```

///

## 运行程序

在你激活虚拟环境后，你可以运行你的程序，它将使用虚拟环境中的 Python 和你在其中安装的软件包。

public final class AsynchronousGet {
  private final OkHttpClient client = new OkHttpClient();

  public void run() throws Exception {
    Request request = new Request.Builder()
        .url("http://publicobject.com/helloworld.txt")
        .build();

    client.newCall(request).enqueue(new Callback() {
      @Override public void onFailure(Call call, IOException e) {
        e.printStackTrace();
      }

이제 `/v1/` 경로에 있는 모든 요청은 Flask 응용 프로그램에서 처리됩니다.

그리고 나머지는 **FastAPI**에 의해 처리됩니다.

실행하면 <a href="http://localhost:8000/v1/" class="external-link" target="_blank">http://localhost:8000/v1/</a>으로 이동해서 Flask의 응답을 볼 수 있습니다:

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

그리고 다음으로 이동하면 <a href="http://localhost:8000/v2" class="external-link" target="_blank">http://localhost:8000/v2</a> Flask의 응답을 볼 수 있습니다:

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

# Move hermetic requirement lock files for NumPy 1 to the root
if [[ "$TFCI_WHL_NUMPY_VERSION" == 1 ]]; then
  cp ./ci/official/requirements_updater/numpy1_requirements/*.txt .
fi

if [[ $TFCI_PYCPP_SWAP_TO_BUILD_ENABLE == 1 ]]; then

    <module name="SuppressionFilter">
        <property name="file" value="${config_loc}/suppressions.xml"/>
    </module>
    <module name="RegexpHeader">
        <property name="headerFile" value="${config_loc}/required-header.txt"/>
    </module>
    <module name="RegexpSingleline">
        <property name="format" value="File \| Settings \| File Templates"/>
    </module>
    <module name="RegexpSingleline">