$form:headers
Such a construction returns hash with all HTTP-response headers set so far.
Names of HTTP-response fields are in uppercase letters. [3.4.4]
Example $response:expires[^date::now(+1)] ^response:headers.foreach[header;value]{
$header - ^if($value is "string" || $value is "int" || $value is "double"){$value}{not printable} }[<br />]
…will output all HTTP-response headers that were set up to that moment.