code: def _is_last_step(self, work_item: WorkItem) -> bool:
      if work_item.forward_only:
          last_phase = Phase.FORWARD
      else:
          last_phase = Phase.BACKWARD
      is_last_phase = work_item.phase == last_phase
      last_microbatch_id = self.num_microbatches - 1
      if self.pp_rank < self.actual_stage_num:
          last_microbatch_id -= 1
      is_last_microbatch = work_item.microbatch_id == last_microbatch_id
      return is_last_phase and is_last_microbatch
  
imports: import threading
  from typing import Callable, Dict, List
  import torch
  from torch._C._distributed_rpc import PyRRef
  from torch.futures import Future
  from colossalai.legacy.pipeline.pipeline_process_group import ppg
  from colossalai.legacy.pipeline.rpc._pipeline_base import Phase, PipelineEngineBase, UniqueKey, WorkerBase, WorkItem
label_desc: Use image node_id 7 for calling the ChimeraWorker obj's underlying member method code with example usage: obj._is_last_step(work_item) and returns: unknown