## Оголошення атрибутів моделі

Ви можете використовувати `Field` з атрибутами моделі:

=== "Python 3.10+"

    ```Python hl_lines="11-14"
    {!> ../../../docs_src/body_fields/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="11-14"
    {!> ../../../docs_src/body_fields/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="12-15"

 *
 * Section Index (1,240 bytes)
 * ===========================
 *
 * Each entry is 4 bytes, and represents all the code points that share a 14-bit prefix. Entries are
 * sorted by this 14-bit prefix.
 *
 * We define these values:
 *
 *  * **b0b1s7**: (b0 << 14) + (b1 << 7)
 *  * **b2b3s2**: (b2 << 9) + (b3 << 2)
 *
 * b0b1s7 is the section prefix. If a section is omitted, that means its ranges data exactly matches

    // Less than 16,834 bytes, because we binary search on a 14-bit index.
    assertThat(compactTable.sections.length).isLessThan(1 shl 14)

    // Less than 65,536 bytes, because we binary search on a 14-bit index with a stride of 4 bytes.
    assertThat(compactTable.ranges.length).isLessThan((1 shl 14) * 4)

    // Less than 16,384 chars, because we index on a 14-bit index in the ranges table.

    ```Python hl_lines="12"
    {!> ../../../docs_src/body_nested_models/tutorial002_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="14"
    {!> ../../../docs_src/body_nested_models/tutorial002_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="14"
    {!> ../../../docs_src/body_nested_models/tutorial002.py!}
    ```

## Set 类型

但是随后我们考虑了一下，意识到标签不应该重复，它们很大可能会是唯一的字符串。

    {!> ../../../docs_src/python_types/tutorial009_py310.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="1  4"
    {!> ../../../docs_src/python_types/tutorial009.py!}
    ```

=== "Python 3.8+ alternative"

    ```Python hl_lines="1  4"
    {!> ../../../docs_src/python_types/tutorial009b.py!}
    ```

#### Sử dụng `Union` hay `Optional`

  ) : MappedRange {
    private val absoluteDelta = abs(codepointDelta)

    val b1: Int
      get() =
        when {
          codepointDelta < 0 -> 0x40 or (absoluteDelta shr 14)
          codepointDelta > 0 -> 0x50 or (absoluteDelta shr 14)
          else -> error("Unexpected codepointDelta of 0")
        }

    val b2: Int
      get() = absoluteDelta shr 7 and 0x7f

    val b3: Int
      get() = absoluteDelta and 0x7f

## 声明模型属性

然后，使用 `Field` 定义模型的属性：

=== "Python 3.10+"

    ```Python hl_lines="11-14"
    {!> ../../../docs_src/body_fields/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="11-14"
    {!> ../../../docs_src/body_fields/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="12-15"

```Python hl_lines="1  4"
{!../../../docs_src/python_types/tutorial009.py!}
```

⚙️ `Optional[str]` ↩️ `str` 🔜 ➡️ 👨‍🎨 ℹ 👆 🔍 ❌ 🌐❔ 👆 💪 🤔 👈 💲 🕧 `str`, 🕐❔ ⚫️ 💪 🤙 `None` 💁‍♂️.

`Optional[Something]` 🤙 ⌨ `Union[Something, None]`, 👫 🌓.

👉 ⛓ 👈 🐍 3️⃣.1️⃣0️⃣, 👆 💪 ⚙️ `Something | None`:

=== "🐍 3️⃣.6️⃣ & 🔛"

    ```Python hl_lines="1  4"

import common.javaHome
import jetbrains.buildServer.configs.kotlin.Project

class PromotionProject(branch: VersionedSettingsBranch) : Project({
    id("Promotion")
    name = "Promotion"

    cleanupRule(historyDays = 14, artifactsDays = 7)

    buildType(SanityCheck)
    buildType(PublishNightlySnapshot(branch))
    buildType(PublishNightlySnapshotFromQuickFeedback(branch))

Це також означає, що в Python 3.10 ви можете використовувати `Something | None`:

=== "Python 3.8 і вище"

    ```Python hl_lines="1  4"
    {!> ../../../docs_src/python_types/tutorial009.py!}
    ```

=== "Python 3.8 і вище - альтернатива"

    ```Python hl_lines="1  4"
    {!> ../../../docs_src/python_types/tutorial009b.py!}
    ```

=== "Python 3.10 і вище"

    ```Python hl_lines="1"