code: function increment(redisClient, amount, keyPrepend, key, callback) {
  
      if (typeof amount !== 'number') {
          callback("increment amount is not number");
          return;
      }
  
      var multi = redisClient.multi();
  
      // Chain each redis command.
      incrementMinute(multi, amount, keyPrepend, key);
      incrementHour(multi, amount, keyPrepend, key);
      incrementDays(multi, amount, keyPrepend, key);
      incrementWeeks(multi, amount, keyPrepend, key);
  
      // Do it
      multi.exec(callback);
  
  }
docs: ## Redis incrementors Main function to increment a key.