WordPress at a glance
function is not described

WP_HTTP_Response::header() public WP 4.4.0

Sets a single HTTP header.

{} It's a method of the class: WP_HTTP_Response{}

No Hooks.

Return

null. Null. Nothing.

Usage

$WP_HTTP_Response = new WP_HTTP_Response();
$WP_HTTP_Response->header( $key, $value, $replace );
$key(string) (required)
Header name.
$value(string) (required)
Header value.
$replace(true|false)
Whether to replace an existing header of the same name.
Default: true

Changelog

Since 4.4.0 Introduced.

Code of WP_HTTP_Response::header() WP 5.7

<?php
public function header( $key, $value, $replace = true ) {
	if ( $replace || ! isset( $this->headers[ $key ] ) ) {
		$this->headers[ $key ] = $value;
	} else {
		$this->headers[ $key ] .= ', ' . $value;
	}
}