```python
from typing import Optional


def say_hi(name: Optional[str]):
    print(f"Hey {name}!")
```

매개변수 `name`은 `Optional[str]`로 정의되어 있지만, 사실 선택적이지 않습니다. 이 매개변수 없이 함수를 호출할 수 없습니다:

```Python
say_hi()  # 이런, 에러가 발생합니다! 😱
```

`name` 매개변수는 기본값이 없기 때문에 여전히 필수입니다(선택적이 아님). 대신, `name`에는 `None`을 전달할 수 있습니다:

```Python
say_hi(name=None)  # 작동합니다. None은 유효합니다 🎉
```

举个例子，看这段函数：

```python
from typing import Optional


def say_hi(name: Optional[str]):
    print(f"Hey {name}!")
```

参数 `name` 被定义为 `Optional[str]`，但它并不是“可选”的，你不能不传这个参数就调用函数：

```Python
say_hi()  # 哎呀，这会报错！😱
```

参数 `name` 仍然是必填的（不是“可选”），因为它没有默认值。不过，`name` 接受 `None` 作为取值：

```Python
say_hi(name=None)  # 这样可以，None 是有效的 🎉
```

好消息是，在大多数情况下，你可以直接使用 `|` 来定义类型联合：

```python

예를 들어 다음 함수가 있다면:

```Python
@lru_cache
def say_hi(name: str, salutation: str = "Ms."):
    return f"Hello {salutation} {name}"
```

프로그램은 다음과 같이 실행될 수 있습니다:

```mermaid
sequenceDiagram

participant code as Code
participant function as say_hi()
participant execute as Execute function

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Camila")

例として次の関数を見てみましょう:

```python
from typing import Optional


def say_hi(name: Optional[str]):
    print(f"Hey {name}!")
```

パラメータ `name` は `Optional[str]` と定義されていますが、任意ではありません。このパラメータなしで関数を呼び出すことはできません:

```Python
say_hi()  # あっ、これはエラーになります！😱
```

`name` パラメータにはデフォルト値がないため、依然として必須（任意ではない）です。ただし、`name` は値として `None` を受け付けます:

```Python
say_hi(name=None)  # これは動作します。None は有効です 🎉
```

例如，如果你有一個函式：

```Python
@lru_cache
def say_hi(name: str, salutation: str = "Ms."):
    return f"Hello {salutation} {name}"
```

你的程式可能會這樣執行：

```mermaid
sequenceDiagram

participant code as Code
participant function as say_hi()
participant execute as Execute function

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Camila")

As an example, let's take this function:

```python
from typing import Optional


def say_hi(name: Optional[str]):
    print(f"Hey {name}!")
```

The parameter `name` is defined as `Optional[str]`, but it is **not optional**, you cannot call the function without the parameter:

```Python
say_hi()  # Oh, no, this throws an error! 😱
```

from typing import Optional


def say_hi(name: Optional[str]):
    print(f"Hey {name}!")
```

參數 `name` 被標註為 `Optional[str]`，但它並不是可選的；你不能在沒有該參數的情況下呼叫這個函式：

```Python
say_hi()  # 糟了，這會拋出錯誤！😱
```

參數 `name` 仍是必填（不是可選），因為它沒有預設值。不過，`name` 可以接受 `None` 作為值：

```Python
say_hi(name=None)  # 這可行，None 是有效的 🎉
```

好消息是，多數情況下你可以直接用 `|` 來定義型別聯集：

```python
def say_hi(name: str | None):
    print(f"Hey {name}!")

```Python
@lru_cache
def say_hi(name: str, salutation: str = "Ms."):
    return f"Hello {salutation} {name}"
```

your program could execute like this:

```mermaid
sequenceDiagram

participant code as Code
participant function as say_hi()
participant execute as Execute function

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Camila")

たとえば、次のような関数があるとします:

```Python
@lru_cache
def say_hi(name: str, salutation: str = "Ms."):
    return f"Hello {salutation} {name}"
```

プログラムは次のように実行されます:

```mermaid
sequenceDiagram

participant code as Code
participant function as say_hi()
participant execute as Execute function

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Camila")

例如，如果你有一个函数：

```Python
@lru_cache
def say_hi(name: str, salutation: str = "Ms."):
    return f"Hello {salutation} {name}"
```

你的程序可能会像这样执行：

```mermaid
sequenceDiagram

participant code as Code
participant function as say_hi()
participant execute as Execute function

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Camila")
        function ->> execute: 执行函数代码