school, if any, to sign a "copyright disclaimer" for the library, if
necessary.  Here is a sample; alter the names:

  Yoyodyne, Inc., hereby disclaims all copyright interest in the
  library `Frob' (a library for tweaking knobs) written by James Random
  Hacker.

  {signature of Ty Coon}, 1 April 1990
  Ty Coon, President of Vice

   * the original exception type.
   *
   * <p>This method always throws, and as such should be called as {@code throw closer.rethrow(e);}
   * to ensure the compiler knows that it will throw.
   *
   * @return this method does not return; it always throws
   * @throws IOException when the given throwable is an IOException
   */

          val domainName = fromSource.readUtf8(domainNameLength.toLong())
          // Resolve HOSTNAME_THAT_ONLY_THE_PROXY_KNOWS to localhost.
          when {
            domainName.equals(HOSTNAME_THAT_ONLY_THE_PROXY_KNOWS, ignoreCase = true) -> {
              InetAddress.getByName("localhost")
            }
            else -> InetAddress.getByName(domainName)
          }
        }

    Class<E> result = classOrNull == null ? (Class<E>) (Class<?>) Object.class : classOrNull;
    return result;
  }

  /*
   * If I understand correctly:
   *
   * This needs to be a @JsMethod so that J2CL knows to look for a JavaScript implemention of
   * it in Platform.native.js. (The JavaScript implementation inline below is visible to *GWT*, but
   * *J2CL* doesn't look at it.)
   *

   * elements than the collection), the element in the array immediately following the end of the
   * collection is set to {@code null}. This is useful in determining the length of the collection
   * <i>only</i> if the caller knows that the collection does not contain any null elements.
   *
   * <p>This method returns the elements in the order they are returned by the collection's
   * iterator.
   *

      clientTestRule.newClientBuilder()
        .proxy(socksProxy.proxy())
        .build()
    val url =
      server.url("/")
        .newBuilder()
        .host(SocksProxy.HOSTNAME_THAT_ONLY_THE_PROXY_KNOWS)
        .build()
    val request = Request.Builder().url(url).build()
    val response1 = client.newCall(request).execute()
    assertThat(response1.body.string()).isEqualTo("abc")

   */
  @Throws(IOException::class)
  fun authenticate(
    route: Route?,
    response: Response,
  ): Request?

  companion object {
    /** An authenticator that knows no credentials and makes no attempt to authenticate. */
    @JvmField
    val NONE: Authenticator = AuthenticatorNone()

    private class AuthenticatorNone : Authenticator {
      override fun authenticate(

 * Self-signed Signature: 799f1d96c6b6793f228d87d3870304606a6b9a2e59897311ac43d1f513ff8d392bc0f...
 * ```
 *
 * In this example the HTTP client already knows and trusts the last certificate, "Entrust Root
 * Certification Authority - G2". That certificate is used to verify the signature of the
 * intermediate certificate, "Entrust Certification Authority - L1M". The intermediate certificate

**FastAPI** knows what to do in each case and how to re-use the same object, so that all the background tasks are merged together and are run in the background afterwards:

=== "Python 3.10+"

    ```Python hl_lines="13  15  22  25"

<img src="/img/tutorial/response-status-code/image01.png">

!!! note
    Some response codes (see the next section) indicate that the response does not have a body.

    FastAPI knows this, and will produce OpenAPI docs that state there is no response body.

## About HTTP status codes

!!! note
    If you already know what HTTP status codes are, skip to the next section.