For example, to declare another response with a status code `404` and a Pydantic model `Message`, you can write:

{* ../../docs_src/additional_responses/tutorial001_py310.py hl[18,22] *}

/// note

Keep in mind that you have to return the `JSONResponse` directly.

///

/// info

The `model` key is not part of OpenAPI.

   * values.length) are all {@code null}.
   */
  @VisibleForTesting transient @Nullable Object @Nullable [] values;

  /**
   * Keeps track of metadata like the number of hash table bits and modifications of this data
   * structure (to make it possible to throw ConcurrentModificationException in the iterator). Note

 * newHasher().putByte(b1).putBytes(new byte[] { b2, b3 }).hash()
 * newHasher().putBytes(new byte[] { b1, b2, b3 }).hash()
 * }
 *
 * <p>If you wish to avoid this, you should either prepend or append the size of each chunk. Keep in
 * mind that when dealing with char sequences, the encoded form of two concatenated char sequences
 * is not equivalent to the concatenation of their encoded form. Therefore, {@link

## Detalles técnicos { #technical-details }

FastAPI implementa algunas mejores prácticas de SSE desde el primer momento.

{* ../../docs_src/server_sent_events/tutorial005_py310.py hl[14] *}

## Technical Details { #technical-details }

FastAPI implements some SSE best practices out of the box.

 * number of streams, dynamically configured with `SETTINGS_MAX_CONCURRENT_STREAMS`. A connection
 * currently carrying zero streams is an idle stream. We keep it alive because reusing an existing
 * connection is typically faster than establishing a new one.
 *
 * When a single logical call requires multiple streams due to redirects or authorization

{* ../../docs_src/server_sent_events/tutorial005_py310.py hl[14] *}

## Технічні деталі { #technical-details }

FastAPI реалізує деякі найкращі практики SSE «з коробки».

   * IllegalArgumentException} if passed a {@code fromKey} less than an earlier {@code fromKey}.
   * However, this method doesn't throw an exception in that situation, but instead keeps the
   * original {@code fromKey}. Similarly, this method keeps the original {@code toKey}, instead of
   * throwing an exception, if passed a {@code toKey} greater than an earlier {@code toKey}.
   */
  @Override

/**
 * Manages reuse of HTTP and HTTP/2 connections for reduced network latency. HTTP requests that
 * share the same [Address] may share a [Connection]. This class implements the policy
 * of which connections to keep open for future use.
 *
 * @constructor Create a new connection pool with tuning parameters appropriate for a single-user
 * application. The tuning parameters in this pool are subject to change in future OkHttp releases.

      }
      return false;
    }

    /**
     * Returns a string in the format specified by {@link MoreObjects#toStringHelper(Object)}.
     *
     * <p>After calling this method, you can keep adding more properties to later call toString()
     * again and get a more complete representation of the same object; but properties cannot be
     * removed, so this only allows limited reuse of the helper instance. The helper allows