return w.streamErr
}

type metacacheBlock struct {
	data  []byte
	n     int
	First string `json:"f"`
	Last  string `json:"l"`
	EOS   bool   `json:"eos,omitempty"`
}

func (b metacacheBlock) headerKV() map[string]string {
	json := jsoniter.ConfigCompatibleWithStandardLibrary
	v, err := json.Marshal(b)
	if err != nil {
		bugLogIf(context.Background(), err) // Unlikely
		return nil
	}

		bugLogIf(ctx, err)
		custom := b.headerKV()
		_, err = er.putMetacacheObject(ctx, o.objectPath(b.n), NewPutObjReader(r), ObjectOptions{
			UserDefined: custom,
		})
		if err != nil {
			mc.setErr(err.Error())
			cancel()
			return err
		}
		if b.n == 0 {
			return nil
		}
		// Update block 0 metadata.
		var retries int
		for {
			meta := b.headerKV()
			fi := FileInfo{

  }

  @Test fun headersNotEquals() {
    val headers1 =
      Headers
        .Builder()
        .add("Connection", "close")
        .add("Transfer-Encoding", "chunked")
        .build()
    val headers2 =
      Headers
        .Builder()
        .add("Connection", "keep-alive")
        .add("Transfer-Encoding", "chunked")
        .build()
    assertThat(headers2).isNotEqualTo(headers1)

Und da die `Response` häufig zum Setzen von Headern und Cookies verwendet wird, stellt **FastAPI** diese auch unter `fastapi.Response` bereit.

///

## Benutzerdefinierte Header

Beachten Sie, dass benutzerdefinierte proprietäre Header <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">mittels des Präfix 'X-'</a> hinzugefügt werden können.

# Parámetros de Header

Puedes definir los parámetros de Header de la misma manera que defines los parámetros de `Query`, `Path` y `Cookie`.

## Importar `Header`

Primero importa `Header`:

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[3] *}

## Declarar parámetros de `Header`

Luego declara los parámetros de header usando la misma estructura que con `Path`, `Query` y `Cookie`.

    fun build(): Headers = commonBuild()
  }

  companion object {
    /** Empty headers. */
    @JvmField
    val EMPTY = Headers(emptyArray())

    /**
     * Returns headers for the alternating header names and values. There must be an even number of
     * arguments, and they must alternate between header names and values.
     */
    @JvmStatic
    @JvmName("of")

# Header Parameters { #header-parameters }

You can define Header parameters the same way you define `Query`, `Path` and `Cookie` parameters.

## Import `Header` { #import-header }

First import `Header`:

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[3] *}

## Declare `Header` parameters { #declare-header-parameters }

Then declare the header parameters using the same structure as with `Path`, `Query` and `Cookie`.

func setEventStreamHeaders(w http.ResponseWriter) {
	w.Header().Set(xhttp.ContentType, "text/event-stream")
	w.Header().Set(xhttp.CacheControl, "no-cache") // nginx to turn off buffering
	w.Header().Set("X-Accel-Buffering", "no")      // nginx to turn off buffering
}

// Write http common headers
func setCommonHeaders(w http.ResponseWriter) {
	// Set the "Server" http header.
	w.Header().Set(xhttp.ServerInfo, MinioStoreName)

# Header Parameter Models { #header-parameter-models }

If you have a group of related **header parameters**, you can create a **Pydantic model** to declare them.

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

/// note | Detalhes Técnicos

`Header` é uma classe "irmã" de `Path`, `Query` e `Cookie`. Ela também herda da mesma classe em comum `Param`.

Mas lembre-se que quando você importa `Query`, `Path`, `Header`, e outras de `fastapi`, elas são na verdade funções que retornam classes especiais.

///

/// info