def stats(contents={}, &callback)
      send_request Request::Stats.new(contents) do |result|
        callback.call result

        if result[:status] == Errors::NO_ERROR && result[:key] != ''
          :proceed
        end
      end
    end
def stats(contents={}, &callback)
      send_request Request::Stats.new(contents) do |result|
        callback.call result

        if result[:status] == Errors::NO_ERROR && result[:key] != ''
          :proceed
        end
      end
    end
Callback will be called multiple times