private function set($key, $value) {
		if (!isset($_SESSION[self::SESSION_KEY_FLASH])) {
			$_SESSION[self::SESSION_KEY_FLASH] = [];
		}

		$_SESSION[self::SESSION_KEY_FLASH][$key] = (string) $value;
	}
private function set($key, $value) {
		if (!isset($_SESSION[self::SESSION_KEY_FLASH])) {
			$_SESSION[self::SESSION_KEY_FLASH] = [];
		}

		$_SESSION[self::SESSION_KEY_FLASH][$key] = (string) $value;
	}
private function set ( $ key , $ value ) { if ( ! isset ( $ _SESSION [ self :: SESSION_KEY_FLASH ] ) ) { $ _SESSION [ self :: SESSION_KEY_FLASH ] = [ ] ; } $ _SESSION [ self :: SESSION_KEY_FLASH ] [ $ key ] = ( string ) $ value ; }
Writes a flash message of the specified type

The message will live until retrieved again, which is usually done on the very next request

@param string $key the type of the message (usually one of the constants in this class starting with `FLASH_KEY_`)
@param string $value the message to store
Writes a flash message of the specified type