code: func (s *Store) getNodeCheckTxn(tx *memdb.Txn, nodeName string, checkID types.CheckID) (uint64, *structs.HealthCheck, error) {
  	// Get the table index.
  	idx := maxIndexTxn(tx, "checks")
  
  	// Return the check.
  	check, err := tx.First("checks", "id", nodeName, string(checkID))
  	if err != nil {
  		return 0, nil, fmt.Errorf("failed check lookup: %s", err)
  	}
  
  	if check != nil {
  		return idx, check.(*structs.HealthCheck), nil
  	}
  	return idx, nil, nil
  }
docs: // nodeCheckTxn is used as the inner method to handle reading a health check
  // from the state store.