code: func NewMeta(txn kv.Transaction, jobListKeys ...JobListKeyType) *Meta {
  	txn.SetOption(kv.Priority, kv.PriorityHigh)
  	txn.SetOption(kv.SyncLog, true)
  	t := structure.NewStructure(txn, txn, mMetaPrefix)
  	listKey := DefaultJobListKey
  	if len(jobListKeys) != 0 {
  		listKey = jobListKeys[0]
  	}
  	return &Meta{txn: t,
  		StartTS:    txn.StartTS(),
  		jobListKey: listKey,
  	}
  }
docs: // NewMeta creates a Meta in transaction txn.
  // If the current Meta needs to handle a job, jobListKey is the type of the job's list.