code: def __repr__(self):
      return (
          "num map tasks per round (num args per merge task): "
          f"{self.num_map_tasks_per_round}\n"
          f"num rounds (num args per reduce task): {self.num_rounds}\n"
          "merge task placement: \n"
          f"{self.merge_schedule}"
      )
  
imports: import math
  from typing import Any, Callable, Dict, List, Optional, Tuple, TypeVar, Union
  import ray
  from ray.data._internal.dataset_logger import DatasetLogger
  from ray.data._internal.execution.interfaces import RefBundle, TaskContext
  from ray.data._internal.planner.exchange.interfaces import ExchangeTaskScheduler, ExchangeTaskSpec
  from ray.data._internal.progress_bar import ProgressBar
  from ray.data._internal.remote_fn import cached_remote_fn
  from ray.data._internal.stats import StatsDict
  from ray.data.block import Block, BlockAccessor, BlockExecStats, BlockMetadata
  from ray.data.context import DataContext
  from ray.types import ObjectRef
  from ray.util.scheduling_strategies import NodeAffinitySchedulingStrategy
label_desc: Use image node_id 3 for calling the _PushBasedShuffleStage obj's underlying member method code with example usage: obj.__repr__() and returns: str, self, str, self, str, self