code: func (a *dbPortAllocator) Get() (int64, error) {
  	sql := `UPDATE ports SET taken = true WHERE port = (SELECT port FROM ports WHERE taken IS NULL ORDER BY port ASC LIMIT 1) RETURNING port`
  	var port int64
  	err := a.db.QueryRow(sql).Scan(&port)
  	return port, err
  }
docs: // Get finds an existing allocated port from the `ports` table. If one is not
  // allocated for the process, it allocates one and returns it.