# Advanced Python Types { #advanced-python-types }

Here are some additional ideas that might be useful when working with Python types.

## Using `Union` or `Optional` { #using-union-or-optional }

If your code for some reason can't use `|`, for example if it's not in a type annotation but in something like `response_model=`, instead of using the vertical bar (`|`) you can use `Union` from `typing`.

# Response Headers { #response-headers }

## Use a `Response` parameter { #use-a-response-parameter }

You can declare a parameter of type `Response` in your *path operation function* (as you can do for cookies).

And then you can set headers in that *temporal* response object.

{* ../../docs_src/response_headers/tutorial002_py310.py hl[1, 7:8] *}

And then you can return any object you need, as you normally would (a `dict`, a database model, etc).

* **Freedom**: No data validation. No schemas. No constraints. Just vibes. ✨
* **Flexibility**: The request can be anything. The response can be anything. Who needs types anyway?
* **No documentation**: Why document your API when an LLM can figure it out? Auto-generated OpenAPI docs are *so* 2020.
* **No serialization**: Just pass the raw, unstructured data around. Serialization is for people who don't trust their LLMs.

# Run a Server Manually { #run-a-server-manually }

## Use the `fastapi run` Command { #use-the-fastapi-run-command }

In short, use `fastapi run` to serve your FastAPI application:

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> run <u style="text-decoration-style:solid">main.py</u>

  <span style="background-color:#009485"><font color="#D3D7CF"> FastAPI </font></span>  Starting production server 🚀

  }
  Import-Module $PSHOME\Modules\Microsoft.PowerShell.Utility -Function Get-FileHash
  if ((Get-FileHash "$TMP_DOWNLOAD_DIR/$distributionUrlName" -Algorithm SHA256).Hash.ToLower() -ne $distributionSha256Sum) {

```

would be the same as going to:

```
http://127.0.0.1:8000/items/?skip=0&limit=10
```

But if you go to, for example:

```
http://127.0.0.1:8000/items/?skip=20
```

The parameter values in your function will be:

* `skip=20`: because you set it in the URL
* `limit=10`: because that was the default value

## Optional parameters { #optional-parameters }

	lru := lru.NewLRU[string, int](10, nil, time.Hour)
	lru.Add("key1", 1)
	lru.Add("key1", 2)

	if value, ok := lru.Get("key1"); !ok || value != 2 {
		t.Errorf("Expected value to be updated to 2, got %v", value)
	}
}

func TestLRU_Add_NewKey_AddsEntry(t *testing.T) {
	lru := lru.NewLRU[string, int](10, nil, time.Hour)
	lru.Add("key1", 1)

	if value, ok := lru.Get("key1"); !ok || value != 1 {

## Architecture Standards

**Experimental!**

We'd like to capture our architectural decisions about the build tool as [Architectural Decision Records (ADRs)](https://adr.github.io/).
For now we just have this global repository of ADRs.
If we see fit, we can break these out to per-platform ones, or keep a hybrid approach to having global and platform-specific ADSs.

Our aim is to keep the process lightweight and approachable.

Directory for log files of DBFlute tasks

If your execution of DBFlute task fails,

@app.get("/portal")
async def get_portal(teleport: bool = False) -> Response | dict:
    if teleport:
        return RedirectResponse(url="https://www.youtube.com/watch?v=dQw4w9WgXcQ")