val derReader = DerReader(buffer)

    derReader.read("test") { header ->
      assertThat(header.tag).isEqualTo(7L)
      assertThat(header.tagClass).isEqualTo(DerHeader.TAG_CLASS_APPLICATION)
      assertThat(header.length).isEqualTo(7L)

      derReader.read("test") { header2 ->
        assertThat(header2.tag).isEqualTo(3L)
        assertThat(header2.tagClass).isEqualTo(DerHeader.TAG_CLASS_APPLICATION)

                                "Header One": {
                                    "summary": "Header One Summary",
                                    "description": "Header One Description",
                                    "value": "header1",
                                },
                                "Header Two": {"value": "header2"},
                            },
                        }

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.

    /**
     * Add a header with the specified name and formatted date. Does validation of header names and
     * value.
     */
    fun add(
      name: String,
      value: Date,
    ) = add(name, value.toHttpDateString())

    /**
     * Add a header with the specified name and formatted instant. Does validation of header names
     * and value.
     */

// functionality to handle SSE-C copy requests.
var SSECopy = ssecCopy{}

type ssecCopy struct{}

// IsRequested returns true if the HTTP headers contains
// at least one SSE-C copy header. Regular SSE-C headers
// are ignored.
func (ssecCopy) IsRequested(h http.Header) bool {
	if _, ok := h[xhttp.AmzServerSideEncryptionCopyCustomerAlgorithm]; ok {
		return true
	}

	// Header indicates that this request is a replication request to create a REPLICA
	MinIOSourceReplicationRequest = "X-Minio-Source-Replication-Request"
	// Header checks replication permissions without actually completing replication
	MinIOSourceReplicationCheck = "X-Minio-Source-Replication-Check"
	// Header indicates replication reset status.
	MinIOReplicationResetStatus = "X-Minio-Replication-Reset-Status"

    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)
    assertThat(headers2.hashCode()).isNotEqualTo(headers1.hashCode().toLong())
  }

///

## Duplicate headers

It is possible to receive duplicate headers. That means, the same header with multiple values.

You can define those cases using a list in the type declaration.

You will receive all the values from the duplicate header as a Python `list`.

```

////

**FastAPI** will **extract** the data for **each field** from the **headers** in the request and give you the Pydantic model you defined.

## Check the Docs

You can see the required headers in the docs UI at `/docs`:

<div class="screenshot">
<img src="/img/tutorial/header-param-models/image01.png">
</div>

## Forbid Extra Headers

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)