```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

Internamente, `open("./somefile.txt")` crea un objeto llamado "Context Manager".

Cuando el bloque `with` termina, se asegura de cerrar el archivo, incluso si hubo excepciones.

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

Под капотом вызов `open("./somefile.txt")` создаёт объект, называемый «контекстным менеджером».

Когда блок `with` завершается, он обязательно закрывает файл, даже если были исключения.

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

Im Hintergrund erstellt das `open("./somefile.txt")` ein Objekt, das als „Kontextmanager“ bezeichnet wird.

/// tip

You can use `async` or regular functions.

**FastAPI** will do the right thing with each, the same as with normal dependencies.

///

## A dependency with `yield` and `try` { #a-dependency-with-yield-and-try }

If you use a `try` block in a dependency with `yield`, you'll receive any exception that was thrown when using the dependency.

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

Por baixo dos panos, o código `open("./somefile.txt")` cria um objeto que é chamado de "Gerenciador de Contexto".

Quando o bloco `with` finaliza, ele se certifica de fechar o arquivo, mesmo que tenha ocorrido alguma exceção.

* 3.2.1 [Generate a private key with ECDSA](#generate-private-key-with-ecdsa)
* 3.2.2 [Generate a private key with RSA](#generate-private-key-with-rsa)
* 3.2.3 [Generate a self-signed certificate](#generate-a-self-signed-certificate)

#### 3.2.1 Generate a private key with ECDSA

Use the following command to generate a private key with ECDSA:

```sh

    "groups" : [ {
      "testProject" : "nowInAndroidBuild",
      "coverage" : {
        "per_commit" : [ "linux", "windows", "macOs" ]
      }
    } ]
  }, {
    "testId" : "org.gradle.performance.regression.android.RealLifeAndroidBuildPerformanceTest.calculate task graph with test finalizer",
    "groups" : [ {

/// note

Notice the header `Authorization`, with a value that starts with `Bearer `.

///

## Advanced usage with `scopes` { #advanced-usage-with-scopes }

OAuth2 has the notion of "scopes".

You can use them to add a specific set of permissions to a JWT token.

Then you can give this token to a user directly or a third party, to interact with your API with a set of restrictions.

	disk, err := newLocalXLStorage(tmpPath)
	if err != nil {
		t.Fatalf("Initializing xlStorage failed with %s.", err)
	}

	// Attempt to create a volume to verify the permissions later.
	// MakeVol creates directory with 0777 perms.
	if err = disk.MakeVol(t.Context(), testCase.volName); err != nil {
		t.Fatalf("Creating a volume failed with %s expected to pass.", err)
	}

	// Attempt to create a file to verify the permissions later.

So, you can use it with:

{* ../../docs_src/path_params/tutorial004_py39.py hl[6] *}

/// tip

You might need the parameter to contain `/home/johndoe/myfile.txt`, with a leading slash (`/`).

In that case, the URL would be: `/files//home/johndoe/myfile.txt`, with a double slash (`//`) between `files` and `home`.

///

## Recap { #recap }