    # File lib/active_support/vendor/memcache-client-1.6.5/memcache.rb, line 580
      def cache_incr(server, cache_key, amount)
        with_socket_management(server) do |socket|
          socket.write "incr #{cache_key} #{amount}\r\n"
          text = socket.gets
          raise_on_error_response! text
          return nil if text == "NOT_FOUND\r\n"
          return text.to_i
        end
      end