this.url = url
      }

    /**
     * Sets the URL target of this request.
     *
     * @throws IllegalArgumentException if [url] is not a valid HTTP or HTTPS URL. Avoid this
     *     exception by calling [HttpUrl.parse]; it returns null for invalid URLs.
     */
    open fun url(url: String): Builder {
      return url(canonicalUrl(url).toHttpUrl())
    }

    /**
     * Sets the URL target of this request.

- [`KT-56421`](https://youtrack.jetbrains.com/issue/KT-56421) Gradle: plugin should not use BasePluginExtension deprecated properties
- [`KT-55241`](https://youtrack.jetbrains.com/issue/KT-55241) Gradle: the VariantImplementationFactories build service state is not persistent making impossible to access factories with configuration cache lazily

    assertThat(request.tag(String::class.java)).isSameAs(stringTag)
    assertThat(request.tag(Long::class.javaObjectType)).isSameAs(longTag)
  }

  /** Confirm that we don't accidentally share the backing map between objects. */
  @Test
  fun tagsAreImmutable() {
    val builder =
      Request.Builder()
        .url("https://square.com")
    val requestA = builder.tag(String::class.java, "a").build()

{!../../../docs_src/custom_response/tutorial004.py!}
```

In this example, the function `generate_html_response()` already generates and returns a `Response` instead of returning the HTML in a `str`.

By returning the result of calling `generate_html_response()`, you are already returning a `Response` that will override the default **FastAPI** behavior.

But at some point, there was no other option than creating something that provided all these features, taking the best ideas from previous tools, and combining them in the best way possible, using language features that weren't even available before (Python 3.6+ type hints).

</blockquote>

## Investigation

    But **FastAPI** will know that it has to solve `query_extractor` first, to pass the results of that to `query_or_cookie_extractor` while calling it.

```mermaid
graph TB

query_extractor(["query_extractor"])
query_or_cookie_extractor(["query_or_cookie_extractor"])

read_query["/items/"]

import mockwebserver3.Stream
import mockwebserver3.StreamHandler
import okio.utf8Size

private typealias Action = (Stream) -> Unit

/**
 * A scriptable request/response conversation. Create the script by calling methods like
 * [receiveRequest] in the sequence they are run.
 */
class MockStreamHandler : StreamHandler {
  private val actions = LinkedBlockingQueue<Action>()

    ```Python hl_lines="5  22"
    {!> ../../../docs_src/encoder/tutorial001.py!}
    ```

In this example, it would convert the Pydantic model to a `dict`, and the `datetime` to a `str`.

The result of calling it is something that can be encoded with the Python standard <a href="https://docs.python.org/3/library/json.html#json.dumps" class="external-link" target="_blank">`json.dumps()`</a>.

!!! tip
    You'll see what other "things", apart from functions, can be used as dependencies in the next chapter.

Whenever a new request arrives, **FastAPI** will take care of:

* Calling your dependency ("dependable") function with the correct parameters.
* Get the result from your function.
* Assign that result to the parameter in your *path operation function*.

```mermaid
graph TB

    bytesIn.writeByte(0x3F) // Dynamic table size update (size = 55).
    bytesIn.writeByte(0x18)
    hpackReader!!.readHeaders()
    assertThat(hpackReader!!.headerCount).isEqualTo(1)
  }

  /** Header table backing array is initially 8 long, let's ensure it grows.  */
  @Test
  fun dynamicallyGrowsBeyond64Entries() {
    // Lots of headers need more room!
    hpackReader = Hpack.Reader(bytesIn, 16384, 4096)