## 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).

  // Last time the condition transitioned from one status to another.
  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.Time lastTransitionTime = 4;

  // Unique, one-word, CamelCase reason for the condition's last transition.
  // +optional
  optional string reason = 5;

  // Human-readable message indicating details about last transition.
  // +optional
  optional string message = 6;
}

### Preprocess the OpenAPI Specification for the Client Generator

The generated code still has some **duplicated information**.

We already know that this method is related to the **items** because that word is in the `ItemsService` (taken from the tag), but we still have the tag name prefixed in the method name too. 😕

We will probably still want to keep it for OpenAPI in general, as that will ensure that the operation IDs are **unique**.

  // Last time the condition transitioned from one status to another.
  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.Time lastTransitionTime = 4;

  // Unique, one-word, CamelCase reason for the condition's last transition.
  // +optional
  optional string reason = 5;

  // Human-readable message indicating details about last transition.
  // +optional

 *
 * ## Protocol vs Scheme
 *
 * Despite its name, [java.net.URL.getProtocol] returns the [scheme][java.net.URI.getScheme] (http,
 * https, etc.) of the URL, not the protocol (http/1.1, spdy/3.1, etc.). OkHttp uses the word
 * *protocol* to identify how HTTP messages are framed.
 *
 * [ietf_alpn]: http://tools.ietf.org/html/draft-ietf-tls-applayerprotoneg
 */
enum class Protocol(private val protocol: String) {
  /**