code: def is_server_or_cluster_db_address(value):
      
      # check if value is an id string
      id_path = value.split("/")
      id = id_path[0]
      return len(id_path) <= 2 and (repository.lookup_server(id) or
                                    repository.lookup_cluster(id))
docs: checks if the specified value is in the form of
      [server or cluster id][/database]