def to_response response, headers
        body = ""
        response.each do |s|
          body << s.to_s
        end
        ["[#{body},#{headers.to_json.to_s}]"]
      end
def to_response response, headers
        body = ""
        response.each do |s|
          body << s.to_s
        end
        ["[#{body},#{headers.to_json.to_s}]"]
      end
returns the response body: old response body + headers as a JSON array