}
			f.Close()
		}

		bs, err := os.ReadFile(goldenFile)
		if err != nil {
			t.Fatalf("opening golden.txt for package %q: %v", fi.Name(), err)
		}
		wanted := strings.Split(string(bs), "\n")
		slices.Sort(wanted)
		for _, feature := range wanted {
			if feature == "" {
				continue
			}
			_, ok := w.features[feature]
			if !ok {
				t.Errorf("package %s: missing feature %q", fi.Name(), feature)
			}

## Return Type and Data Filtering { #return-type-and-data-filtering }

Let's continue from the previous example. We wanted to **annotate the function with one type**, but we wanted to be able to return from the function something that actually includes **more data**.

    /*
     * Don't bother testing. All non-primitive parameters are used only to construct error messages.
     * We never want to pass null for them, so we haven't annotated them to say that null is
     * allowed. But at the same time, it seems wasteful to bother inserting the checkNotNull calls
     * that NullPointerTester wants.
     *
     * (This empty method disables the automatic null testing provided by PackageSanityTests.)
     */
  }

    /*
     * Don't bother testing. All non-primitive parameters are used only to construct error messages.
     * We never want to pass null for them, so we haven't annotated them to say that null is
     * allowed. But at the same time, it seems wasteful to bother inserting the checkNotNull calls
     * that NullPointerTester wants.
     *
     * (This empty method disables the automatic null testing provided by PackageSanityTests.)
     */
  }

    own the intellectual property, then you'll need to sign an [individual
    CLA][]. Please include your GitHub username.
  - If you work for a company that wants to allow you to contribute your work,
    then you'll need to sign a [corporate CLA][].

You generally only need to submit a CLA once, so if you've already submitted

	for i, v := range vectors {
		r := strings.NewReader(v.in)
		got, err := parsePAX(r)
		if !maps.Equal(got, v.want) && !(len(got) == 0 && len(v.want) == 0) {
			t.Errorf("test %d, parsePAX():\ngot  %v\nwant %v", i, got, v.want)
		}
		if ok := err == nil; ok != v.ok {
			t.Errorf("test %d, parsePAX(): got %v, want %v", i, ok, v.ok)
		}
	}
}

func TestReadOldGNUSparseMap(t *testing.T) {

Used by Starlette:

* [`httpx`](https://www.python-httpx.org) - Required if you want to use the `TestClient`.
* [`jinja2`](https://jinja.palletsprojects.com) - Required if you want to use the default template configuration.

Used by Starlette:

* [`httpx`](https://www.python-httpx.org) - Required if you want to use the `TestClient`.
* [`jinja2`](https://jinja.palletsprojects.com) - Required if you want to use the default template configuration.

      return if (!fieldType.isInstance(value)) null else fieldType.cast(value)
    } catch (_: NoSuchFieldException) {
    }

    c = c.superclass
  }

  // Didn't find the field we wanted. As a last gasp attempt,
  // try to find the value on a delegate.
  if (fieldName != "delegate") {
    val delegate = readFieldOrNull(instance, Any::class.java, "delegate")

You can check it at [http://127.0.0.1:9999/api/v1/docs](http://127.0.0.1:9999/api/v1/docs):

<img src="/img/tutorial/behind-a-proxy/image02.png">

Right as we wanted it. ✔️

This is because FastAPI uses this `root_path` to create the default `server` in OpenAPI with the URL provided by `root_path`.

## Additional servers { #additional-servers }

/// warning