code: func (f *fifoProcessor) Push(cnx redis.Conn, src string, payload []byte) (err error) {
  	_, err = cnx.Do("LPUSH", src, payload)
  	return
  }
docs: // Push implements the `func Push` from `Processor`. It pushes to the left-side
  // of the Redis structure using RPUSH, and returns any errors encountered while
  // runnning that command.