When you create a dependency with `yield`, **FastAPI** will internally create a context manager for it, and combine it with some other related tools.

### Using context managers in dependencies with `yield` { #using-context-managers-in-dependencies-with-yield }

/// warning

This is, more or less, an "advanced" idea.

If you are just starting with **FastAPI** you might want to skip it for now.

/**
 * Example of using a hardware key to perform client auth.
 * Prefer recent JDK builds, and results are temperamental to slight environment changes.
 * Different instructions and configuration may be required for other hardware devices.
 *
 * Using a yubikey device as a SSL key store.
 * https://lauri.võsandi.com/2017/03/yubikey-for-ssh-auth.html
 *
 * Using PKCS11 support in the JDK.

As you saw in the previous chapter about [Deployment Concepts](concepts.md), there are multiple strategies you can use.

Here I'll show you how to use **Uvicorn** with **worker processes** using the `fastapi` command or the `uvicorn` command directly.

/// info

If you are using containers, for example with Docker or Kubernetes, I'll tell you more about that in the next chapter: [FastAPI in Containers - Docker](docker.md).

    TestSuite suite = new TestSuite();
    suite.addTest(
        ListTestSuiteBuilder.using(new ImmutableListOfGenerator())
            .named("ImmutableList")
            .withFeatures(CollectionSize.ANY, SERIALIZABLE, ALLOWS_NULL_QUERIES)
            .createTestSuite());
    suite.addTest(
        ListTestSuiteBuilder.using(new BuilderAddAllListGenerator())
            .named("ImmutableList, built with Builder.add")

   * character set.
   *
   * @since 14.0
   */
  public static CharSource asCharSource(File file, Charset charset) {
    return asByteSource(file).asCharSource(charset);
  }

  /**
   * Returns a new {@link CharSink} for writing character data to the given file using the given

///

## `Field` additional arguments { #field-additional-arguments }

When using `Field()` with Pydantic models, you can also declare additional `examples`:

{* ../../docs_src/schema_extra_example/tutorial002_py310.py hl[2,8:11] *}

## `examples` in JSON Schema - OpenAPI { #examples-in-json-schema-openapi }

When using any of:

* `Path()`
* `Query()`
* `Header()`
* `Cookie()`
* `Body()`
* `Form()`

To add a dependency on Guava testlib using Maven, use the following:

```xml
<dependency>
  <groupId>com.google.guava</groupId>
  <artifactId>guava-testlib</artifactId>
  <version>33.5.0-jre</version>
  <scope>test</scope>
</dependency>
```

To add a dependency using Gradle:

```gradle
dependencies {
  test 'com.google.guava:guava-testlib:33.5.0-jre'
}

    }

    // ////////////////////////////////////////////////////////////////
    // from InputStream to Writer
    //
    /**
     * Copies from an input stream to a writer using the platform default encoding.
     * <p>
     * Neither the input stream nor the writer is closed.
     * </p>
     *
     * @param in the input stream (must not be {@literal null})

Make sure you create a [virtual environment](../virtual-environments.md), activate it, and install `jinja2`:

<div class="termy">

```console
$ pip install jinja2

---> 100%
```

</div>

## Using `Jinja2Templates` { #using-jinja2templates }

* Import `Jinja2Templates`.
* Create a `templates` object that you can reuse later.
* Declare a `Request` parameter in the *path operation* that will return a template.

          echo "Found curl ... using curl"
        fi
        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
            curl -o "$wrapperJarPath" "$jarUrl" -f
        else
            curl --user $MVNW_USERNAME:$MVNW_PASSWORD -o "$wrapperJarPath" "$jarUrl" -f
        fi

    else
        if [ "$MVNW_VERBOSE" = true ]; then
          echo "Falling back to using Java to download"
        fi