def is_chief(task: backend.Task, run_name: str):
  """Returns True if task is chief task in the corresponding run"""
  global run_task_dict
  if run_name not in run_task_dict:
    return True
  task_list = run_task_dict[run_name]
  assert task in task_list, f"Task {task.name} doesn't belong to run {run_name}"
  return task_list[0] == task
Returns True if task is chief task in the corresponding run