Например, вы можете объявить, что значение может быть `str` или `None`:

```python
from typing import Union


def say_hi(name: Union[str, None]):
        print(f"Hi {name}!")
```

В `typing` также есть сокращение, чтобы объявить, что значение может быть `None`, — `Optional`.

Вот совет с моей очень субъективной точки зрения:

- 🚨 Избегайте использования `Optional[SomeType]`

	type (
		Furniture struct {
			gorm.Model
			OwnerID *uint
		}

		Owner struct {
			gorm.Model
			Furnitures []Furniture
			CompanyID  *uint
			Company    Company
		}

		Building struct {
			gorm.Model
			Name    string
			OwnerID *uint
			Owner   Owner
		}
	)

	DB.Migrator().DropTable(&Building{}, &Owner{}, &Furniture{})

the corresponding send on <code>c</code> completes, which is sequenced
before the <code>print</code>.
</p>

<p>
If the channel were buffered (e.g., <code>c = make(chan int, 1)</code>)
then the program would not be guaranteed to print
<code>"hello, world"</code>.  (It might print the empty string,
crash, or do something else.)
</p>

<p class="rule">

from pydantic import BaseModel


class User(BaseModel):
    id: int
    name: str = "John Doe"
    signup_ts: datetime | None = None
    friends: list[int] = []


external_data = {
    "id": "123",
    "signup_ts": "2017-06-01 12:22",
    "friends": [1, "2", b"3"],
}
user = User(**external_data)
print(user)

예를 들어, 어떤 값이 `str` 또는 `None`이 될 수 있다고 선언할 수 있습니다:

```python
from typing import Union


def say_hi(name: Union[str, None]):
        print(f"Hi {name}!")
```

`typing`에는 `None`이 될 수 있음을 선언하는 축약형으로 `Optional`도 있습니다.

아주 개인적인 관점에서의 팁입니다:

- 🚨 `Optional[SomeType]` 사용은 피하세요
- 대신 ✨ **`Union[SomeType, None]`를 사용하세요** ✨.

		Can be repeated to define multiple symbols.
	-I dir1 -I dir2
		Search for #include files in dir1, dir2, etc,
		after consulting $GOROOT/pkg/$GOOS_$GOARCH.
	-S
		Print assembly and machine code.
	-V
		Print assembler version and exit.
	-debug
		Dump instructions as they are parsed.
	-dynlink
		Support references to Go symbols defined in other shared libraries.
	-e

# Code blocks { #code-blocks }

Some text

```python
# This is a sample Python code block
def hello_world():
    # Comment with indentation
    print("Hello, world!")  # Print greeting
```

Some more text

```toml
# This is a sample TOML code block
title = "TOML Example"  # Title of the document
```

And more text

```console
// Use the command "live" and pass the language code as a CLI argument

# Code blocks { #code-blocks }

Some text

```python
# This is a sample Python code block
def hello_world():
    # Comment with indentation
    print("Hello, world!")  # Print greeting
```

Some more text

```toml
# This is a sample TOML code block
title = "TOML Example"  # Title of the document
```

Extra code block

```
$ cd my_project
```

And more text

```console

	var (
		intValue      = math.MaxInt64
		int8Value     = int8(math.MaxInt8)
		int16Value    = int16(math.MaxInt16)
		int32Value    = int32(math.MaxInt32)
		int64Value    = int64(math.MaxInt64)
		uintValue     = uint(math.MaxInt64)
		uint8Value    = uint8(math.MaxUint8)
		uint16Value   = uint16(math.MaxUint16)
		uint32Value   = uint32(math.MaxUint32)
		uint64Value   = uint64(math.MaxInt64)
		maxInt64Plus1 = uint64(math.MaxInt64 + 1)

package dsync

import (
	"math/rand"
	"time"
)

func backoffWait(minSleep, unit, maxSleep time.Duration) func(*rand.Rand, uint) time.Duration {
	if unit > time.Hour {
		// Protect against integer overflow
		panic("unit cannot exceed one hour")
	}
	return func(r *rand.Rand, attempt uint) time.Duration {
		sleep := minSleep
		sleep += unit * time.Duration(attempt)
		if sleep > maxSleep {
			sleep = maxSleep
		}