### Create it

Create a file `main.py` with:

```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

<details markdown="1">

			t.Errorf("got string %q; want %q", b.String(), s)
		}
		if r.Len() != 0 {
			t.Errorf("reader contains %v bytes; want 0", r.Len())
		}
	}
}

func TestReaderLen(t *testing.T) {
	const data = "hello world"
	r := NewReader([]byte(data))
	if got, want := r.Len(), 11; got != want {
		t.Errorf("r.Len(): got %d, want %d", got, want)
	}
	if n, err := r.Read(make([]byte, 10)); err != nil || n != 10 {

Puedes pasar a tus *decoradores de path operation* un parámetro `responses`.

Recibe un `dict`: las claves son los códigos de estado para cada response (como `200`), y los valores son otros `dict`s con la información para cada uno de ellos.

Cada uno de esos `dict`s de response puede tener una clave `model`, conteniendo un modelo de Pydantic, así como `response_model`.

## `Union` o `anyOf` { #union-or-anyof }

Puedes declarar un response que sea la `Union` de dos o más tipos, eso significa que el response sería cualquiera de ellos.

Se definirá en OpenAPI con `anyOf`.

Para hacerlo, usa la anotación de tipos estándar de Python <a href="https://docs.python.org/3/library/typing.html#typing.Union" class="external-link" target="_blank">`typing.Union`</a>:

		if writeErr != ErrWriteOnClosed {
			t.Errorf("got: %q; want: %q", writeErr, ErrWriteOnClosed)
		} else {
			t.Log("ok")
		}
	}
	result := string(buf[0:n])
	if result != "hello" {
		t.Errorf("got: %q; want: %q", result, "hello")
	}
}

func timeout(after time.Duration) (cancel func()) {
	c := time.After(after)
	cc := make(chan struct{})
	go func() {
		select {
		case <-cc:
			return

          "bromfiets=>bromfiets",
          "ei=>eier",
          "kind=>kinder"
        ]
      },
      "english_keywords": {
        "type":       "keyword_marker",
        "keywords":   ["hello"]
      },
      "finnish_stop": {
        "type":       "stop",
        "stopwords":  "_finnish_"
      },
      "finnish_keywords": {
        "type":       "keyword_marker",

        ]
    }


def test_root_token_jessica(client: TestClient):
    response = client.get("/?token=jessica")
    assert response.status_code == 200
    assert response.json() == {"message": "Hello Bigger Applications!"}


def test_root_with_no_token(client: TestClient):
    response = client.get("/")
    assert response.status_code == 422
    assert response.json() == {
        "detail": [

Tarayıcınızı açıp <a href="http://127.0.0.1:8000" class="external-link" target="_blank">http://127.0.0.1:8000</a> bağlantısına gidin.

Şu şekilde bir JSON yanıtı ile karşılaşacağız:

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

### Etkileşimli API Dokümantasyonu

Şimdi <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a> bağlantısını açalım.

	delim    byte
	expected []string
	err      error
}{
	{"", 0, []string{""}, io.EOF},
	{"a\x00", 0, []string{"a\x00"}, nil},
	{"abbbaaaba", 'b', []string{"ab", "b", "b", "aaab"}, nil},
	{"hello\x01world", 1, []string{"hello\x01"}, nil},
	{"foo\nbar", 0, []string{"foo\nbar"}, io.EOF},
	{"alpha\nbeta\ngamma\n", '\n', []string{"alpha\n", "beta\n", "gamma\n"}, nil},

          "bromfiets=>bromfiets",
          "ei=>eier",
          "kind=>kinder"
        ]
      },
      "english_keywords": {
        "type":       "keyword_marker",
        "keywords":   ["hello"]
      },
      "finnish_stop": {
        "type":       "stop",
        "stopwords":  "_finnish_"
      },
      "finnish_keywords": {
        "type":       "keyword_marker",