```Python
q: Union[str, None] = None
```

Ou como em Python 3.10 e versões superiores:

```Python
q: str | None = None
```

Por exemplo:

{* ../../docs_src/body_multiple_params/tutorial004_py310.py hl[26] *}

/// info | Informação

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: Union[bool, None] = None


@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}


@app.put("/items/{item_id}")
def update_item(item_id: int, item: Item):

     *
     * - If the stack overflowed after set()/setValue() stored its result, then a call to
     * setException() will be a no-op because the Future is already done.
     *
     * Both scenarios are bad: The output Future might never complete, or, if it does complete, it
     * might not run some of its listeners. The likely result is that the app will hang. (And of

(prefers-reduced-motion: reduce) {\n  .btn {\n    transition: none;\n  }\n}\n\n.btn:hover {\n  color: #212529;\n  text-decoration: none;\n}\n\n.btn:focus, .btn.focus {\n  outline: 0;\n  box-shadow: none;\n}\n\n.btn.disabled, .btn:disabled {\n  opacity: 0.65;\n  box-shadow: none;\n}\n\n.btn:not(:disabled):not(.disabled) {\n  cursor: pointer;\n}\n\n.btn:not(:disabled):not(.disabled):active, .btn:not(:disabled):not(.disabled).active {\n  box-shadow: none;\n}\n\na.btn.disabled,\nfieldset:disabled a.btn {\n  pointer-events:...

        String result = crawlJob.execute();

        assertNotNull(result);
        assertTrue(result.contains("Web  Config Id: web1"));
        assertTrue(result.contains("File Config Id: NONE"));
        assertTrue(result.contains("Data Config Id: data1"));
    }

    // Test getRunningJobCount method
    public void test_getRunningJobCount() {
        // Skip this test - requires complex DB setup

	}

	opts := madmin.DriveSpeedTestOpts{
		Serial:    serial,
		BlockSize: blockSize,
		FileSize:  fileSize,
	}

	done := keepHTTPResponseAlive(w)
	result := driveSpeedTest(r.Context(), opts)
	done(nil)

	peersLogIf(r.Context(), gob.NewEncoder(w).Encode(result))
}

// GetReplicationMRFHandler - returns replication MRF for bucket

    assertMapEquals(ImmutableSortedMap.of("one", 1), "one", 1);
    assertMapEquals(ImmutableSortedMap.of("one", 1, "two", 2), "one", 1, "two", 2);
    assertMapEquals(
        ImmutableSortedMap.of("one", 1, "two", 2, "three", 3), "one", 1, "three", 3, "two", 2);
    assertMapEquals(
        ImmutableSortedMap.of("one", 1, "two", 2, "three", 3, "four", 4),
        "four",
        4,
        "one",
        1,
        "three",

    // First response is still waiting.
    assertThat(firstResponseCode.get()).isEqualTo(0)
    // Second response is done.
    assertThat(secondResponseCode.get()).isEqualTo(200)
    latch.countDown()
    startsFirst.join()
    // And now it's done!
    assertThat(firstResponseCode.get()).isEqualTo(200)
    // (Still done).
    assertThat(secondResponseCode.get()).isEqualTo(200)
  }

  private fun buildRequestThread(

        .expectCollects(
            new ImmutableTable.Builder<String, String, Integer>()
                .put("one", "uno", 1)
                .put("two", "dos", 2)
                .put("three", "tres", 3)
                .buildOrThrow(),
            immutableCell("one", "uno", 1),
            immutableCell("two", "dos", 2),
            immutableCell("three", "tres", 3));
  }

Seu modelo de resposta pode ter valores padrão, como:

{* ../../docs_src/response_model/tutorial004_py310.py hl[9,11:12] *}

* `description: Union[str, None] = None` (ou `str | None = None` no Python 3.10) tem um padrão de `None`.
* `tax: float = 10.5` tem um padrão de `10.5`.
* `tags: List[str] = []` tem um padrão de uma lista vazia: `[]`.