## Program and Process

We will talk a lot about the running "**process**", so it's useful to have clarity about what it means, and what's the difference with the word "**program**".

### What is a Program

The word **program** is commonly used to describe many things:

* The **code** that you write, the **Python files**.

  // `lastTransitionTime` is the last time the condition transitioned from one status to another.
  optional k8s.io.apimachinery.pkg.apis.meta.v1.Time lastTransitionTime = 3;

  // `reason` is a unique, one-word, CamelCase reason for the condition's last transition.
  optional string reason = 4;

  // `message` is a human-readable message indicating details about last transition.
  optional string message = 5;
}

  // `lastTransitionTime` is the last time the condition transitioned from one status to another.
  optional k8s.io.apimachinery.pkg.apis.meta.v1.Time lastTransitionTime = 3;

  // `reason` is a unique, one-word, CamelCase reason for the condition's last transition.
  optional string reason = 4;

  // `message` is a human-readable message indicating details about last transition.
  optional string message = 5;
}

```Python hl_lines="7"
{!../../../docs_src/path_params_numeric_validations/tutorial003.py!}
```

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

Both are equivalent and underneath they are the same, but I would recommend `Union` instead of `Optional` because the word "**optional**" would seem to imply that the value is optional, and it actually means "it can be `None`", even if it's not optional and is still required.

I think `Union[SomeType, None]` is more explicit about what it means.

* ✏ Fix typo about file path in `docs/en/docs/tutorial/bigger-applications.md`. PR [#3285](https://github.com/tiangolo/fastapi/pull/3285) by [@HolyDorus](https://github.com/HolyDorus).
* ✏ Re-word to clarify test client in `docs/en/docs/tutorial/testing.md`. PR [#3382](https://github.com/tiangolo/fastapi/pull/3382) by [@Bharat123rox](https://github.com/Bharat123rox).

## 按需对参数排序的技巧

如果你想不使用 `Query` 声明没有默认值的查询参数 `q`，同时使用 `Path` 声明路径参数 `item_id`，并使它们的顺序与上面不同，Python 对此有一些特殊的语法。

传递 `*` 作为函数的第一个参数。

Python 不会对该 `*` 做任何事情，但是它将知道之后的所有参数都应作为关键字参数（键值对），也被称为 <abbr title="来自：K-ey W-ord Arg-uments"><code>kwargs</code></abbr>，来调用。即使它们没有默认值。

```Python hl_lines="7"
{!../../../docs_src/path_params_numeric_validations/tutorial003.py!}
```

## 数值校验：大于等于

  // `lastTransitionTime` is the last time the condition transitioned from one status to another.
  optional k8s.io.apimachinery.pkg.apis.meta.v1.Time lastTransitionTime = 3;

  // `reason` is a unique, one-word, CamelCase reason for the condition's last transition.
  optional string reason = 4;

  // `message` is a human-readable message indicating details about last transition.
  optional string message = 5;
}

  // `lastTransitionTime` is the last time the condition transitioned from one status to another.
  optional k8s.io.apimachinery.pkg.apis.meta.v1.Time lastTransitionTime = 3;

  // `reason` is a unique, one-word, CamelCase reason for the condition's last transition.
  optional string reason = 4;

  // `message` is a human-readable message indicating details about last transition.
  optional string message = 5;
}

O Python não vai fazer nada com esse `*`, mas ele vai saber que a partir dali os parâmetros seguintes deverão ser chamados argumentos nomeados (pares chave-valor), também conhecidos como <abbr title="Do inglês: K-ey W-ord Arg-uments"><code>kwargs</code></abbr>. Mesmo que eles não possuam um valor padrão.

```Python hl_lines="7"
{!../../../docs_src/path_params_numeric_validations/tutorial003.py!}
```