code: def set_topological_dag_upstreams(dag, ops, op_runs, runs_by_ops):
      sorted_ops = dags.sort_topologically(dag=dag)
      for op_id in sorted_ops:
          op_run_id = runs_by_ops[op_id]
          op_run = op_runs[op_run_id]
          set_op_upstreams(op_run=op_run, op=ops[op_id])