code: def store_alias(self, seq_id, namespace, alias):
          
  
          if not self._writeable:
              raise RuntimeError("Cannot write -- opened read-only")
  
          log_pfx = "store({q},{n},{a})".format(n=namespace, a=alias, q=seq_id)
          try:
              c = self._db.execute("insert into seqalias (seq_id, namespace, alias) values (?, ?, ?)", (seq_id, namespace,
                                                                                                        alias))
              # success => new record
              return c.lastrowid
          except sqlite3.IntegrityError:
              pass
  
          # IntegrityError fall-through
  
          # existing record is guaranteed to exist uniquely; fetchone() should always succeed
          current_rec = self.find_aliases(namespace=namespace, alias=alias).fetchone()
  
          # if seq_id matches current record, it's a duplicate (seq_id, namespace, alias) tuple
          # and we return current record
          if current_rec["seq_id"] == seq_id:
              _logger.debug(log_pfx + ": duplicate record")
              return current_rec["seqalias_id"]
  
          # otherwise, we're reassigning; deprecate old record, then retry
          _logger.debug(log_pfx + ": collision; deprecating {s1}".format(s1=current_rec["seq_id"]))
          self._db.execute("update seqalias set is_current = 0 where seqalias_id = ?", [current_rec["seqalias_id"]])
          return self.store_alias(seq_id, namespace, alias)
docs: associate a namespaced alias with a sequence
  
          Alias association with sequences is idempotent: duplicate
          associations are discarded silently.