def check!(request)
      @check_headers.each do |header_name|
        values = @checks[header_name]
        header = request.send(header_name)
        raise AcceptError unless values.any? {|v| header.accept?(v) }
      end
    end
def check!(request)
      @check_headers.each do |header_name|
        values = @checks[header_name]
        header = request.send(header_name)
        raise AcceptError unless values.any? {|v| header.accept?(v) }
      end
    end
Raises an AcceptError if this server is not able to serve an acceptable
 response.