module Net::HTTPHeader

def digest_auth(username, password, response)
  authenticator = DigestAuthenticator.new(
    username,
    password,
    @method,
    @path,
    response
  )
  authenticator.authorization_header.each do |v|
    add_field('Authorization', v)
  end
  authenticator.cookie_header.each do |v|
    add_field('Cookie', v)
  end
end