assertMinSize(union(emptySet(), emptySet()), 0);
    assertMinSize(union(setSize(2), setSize(3)), 3);
    assertMinSize(union(setSize(3), setSize(2)), 3);
    assertMinSize(union(setSizeRange(10, 20), setSizeRange(11, 12)), 11);
    assertMinSize(union(setSizeRange(11, 12), setSizeRange(10, 20)), 11);
  }

  public void testUnion_maxSize() {
    assertMaxSize(union(emptySet(), emptySet()), 0);

➡️ ✊ 👉 🈸 🖼:

{* ../../docs_src/query_params_str_validations/tutorial001.py hl[9] *}

🔢 🔢 `q` 🆎 `Union[str, None]` (⚖️ `str | None` 🐍 3️⃣.1️⃣0️⃣), 👈 ⛓ 👈 ⚫️ 🆎 `str` ✋️ 💪 `None`, & 👐, 🔢 💲 `None`, FastAPI 🔜 💭 ⚫️ 🚫 ✔.

/// note

FastAPI 🔜 💭 👈 💲 `q` 🚫 ✔ ↩️ 🔢 💲 `= None`.

 `Union` `Union[str, None]` 🔜 ✔ 👆 👨‍🎨 🤝 👆 👍 🐕‍🦺 & 🔍 ❌.

///

## 🌖 🔬

## `Union` o `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 el type hint estándar de Python <a href="https://docs.python.org/3/library/typing.html#typing.Union" class="external-link" target="_blank">`typing.Union`</a>:

/// note | Nota

```Python
q: str
```

вместо:

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

Но у нас query-параметр определён как `Query`. Например:

//// tab | Annotated

```Python
q: Annotated[Union[str, None], Query(min_length=3)] = None
```

////

//// tab | без Annotated

```Python
q: Union[str, None] = Query(default=None, min_length=3)
```

////

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

You can declare a response to be the `Union` of two or more types, that means, that the response would be any of them.

It will be defined in OpenAPI with `anyOf`.

To do that, use the standard Python type hint <a href="https://docs.python.org/3/library/typing.html#typing.Union" class="external-link" target="_blank">`typing.Union`</a>:

/// note

```Python
q: str
```

statt:

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

Aber jetzt deklarieren wir den Parameter mit `Query`, wie in:

//// tab | Annotiert

```Python
q: Annotated[Union[str, None], Query(min_length=3)] = None
```

////

//// tab | Nicht annotiert

```Python
q: Union[str, None] = Query(default=None, min_length=3)
```

////

## Приклад

### Створіть

* Створіть файл `main.py` з:

```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">

```

////

#### Using `Union` or `Optional` { #using-union-or-optional }

If you are using a Python version below 3.10, here's a tip from my very **subjective** point of view:

* 🚨 Avoid using `Optional[SomeType]`
* Instead ✨ **use `Union[SomeType, None]`** ✨.

import static com.google.common.collect.Multisets.difference;
import static com.google.common.collect.Multisets.intersection;
import static com.google.common.collect.Multisets.sum;
import static com.google.common.collect.Multisets.union;
import static com.google.common.collect.Multisets.unmodifiableMultiset;
import static java.util.Arrays.asList;
import static java.util.Collections.sort;

import com.google.common.annotations.GwtIncompatible;

{* ../../docs_src/extra_models/tutorial002_py310.py hl[7,13:14,17:18,21:22] *}

## `Union` 또는 `anyOf`

두 가지 이상의 타입을 포함하는 `Union`으로 응답을 선언할 수 있습니다. 이는 응답이 그 중 하나의 타입일 수 있음을 의미합니다.

OpenAPI에서는 이를 `anyOf`로 정의합니다.

이를 위해 표준 Python 타입 힌트인 <a href="https://docs.python.org/3/library/typing.html#typing.Union" class="external-link" target="_blank">`typing.Union`</a>을 사용할 수 있습니다:

/// note | 참고