}

  /**
   * Wrapper for {@link Map#get(Object)} that forces the caller to pass in a key of the same type as
   * the map. Besides being slightly shorter than code that uses {@link #getMap()}, it also ensures
   * that callers don't pass an {@link Entry} by mistake.
   */
  protected V get(K key) {
    return getMap().get(key);
  }

  protected final K k0() {

            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_set_header X-NginX-Proxy true;

            # This is necessary to pass the correct IP to be hashed
            real_ip_header X-Real-IP;

            proxy_connect_timeout 300;
            
            # To support websocket
            proxy_http_version 1.1;

#### Password hashing { #password-hashing }

"Hashing" means: converting some content (a password in this case) into a sequence of bytes (just a string) that looks like gibberish.

Whenever you pass exactly the same content (exactly the same password) you get exactly the same gibberish.

But you cannot convert from the gibberish back to the password.

##### Why use password hashing { #why-use-password-hashing }

But if you are certain that the content that you are returning is **serializable with JSON**, you can pass it directly to the response class and avoid the extra overhead that FastAPI would have by passing your return content through the `jsonable_encoder` before passing it to the response class.

            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_set_header X-NginX-Proxy true;

            # This is necessary to pass the correct IP to be hashed
            real_ip_header X-Real-IP;

            proxy_connect_timeout 300;
            
            # To support websocket
            proxy_http_version 1.1;

    return delegate().apply(key);
  }

  @Override
  public void refresh(K key) {
    delegate().refresh(key);
  }

  /**
   * A simplified version of {@link ForwardingLoadingCache} where subclasses can pass in an already
   * constructed {@link LoadingCache} as the delegate.
   *
   * @since 10.0
   */
  public abstract static class SimpleForwardingLoadingCache<K, V>
      extends ForwardingLoadingCache<K, V> {

You can also add headers when you return a `Response` directly.

Create a response as described in [Return a Response Directly](response-directly.md){.internal-link target=_blank} and pass the headers as an additional parameter:

{* ../../docs_src/response_headers/tutorial001.py hl[10:12] *}

/// note | Technical Details

            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_set_header X-NginX-Proxy true;

            # This is necessary to pass the correct IP to be hashed
            real_ip_header X-Real-IP;

            proxy_connect_timeout 300;
            
            # To support websocket
            proxy_http_version 1.1;

* Ele pega cada **requisição** que chega ao seu aplicativo.
* Ele pode então fazer algo com essa **requisição** ou executar qualquer código necessário.
* Então ele passa a **requisição** para ser processada pelo resto do aplicativo (por alguma *operação de rota*).
* Ele então pega a **resposta** gerada pelo aplicativo (por alguma *operação de rota*).

   *       in the {@code exceptions} collection.
   * </ul>
   *
   * <p>Though this method takes any {@link Collection}, it often makes most sense to pass a {@link
   * java.util.List} or some other collection that preserves the order in which the exceptions got
   * added.
   *
   * @throws NullPointerException if {@code exceptions} is null