code: func (mc MongoClient) EventsByCreationTime(startTime, endTime int64, limit int) ([]contract.Event, error) {
  	query := bson.M{"created": bson.M{
  		"$gte": startTime,
  		"$lte": endTime,
  	}}
  	return mc.mapEvents(mc.getEventsLimit(query, limit))
  }
docs: // Return a list of events whose creation time is between startTime and endTime
  // Limit the number of results by limit