code: def _step_str(state: TrainerState) -> str:
      total_step = state.num_step_per_epoch
      if state.step == -1:
          current_step = -1
      else:
          current_step = state.step % total_step
          if current_step == 0:
              current_step = total_step if state.step > 0 else 0
      length = len(str(total_step))
      return f"[{current_step:{length}d} / {total_step}]"
  
imports: import os
  import json
  import time
  import shutil
  import getpass
  import platform
  from typing import Any
  from typing import Dict
  from typing import Optional
  from cftool.misc import lock_manager
  from cftool.misc import print_warning
  from cftool.misc import fix_float_to_length
  from ..schema import ITrainer
  from ..schema import StepOutputs
  from ..schema import TrainerState
  from ..schema import MetricsOutputs
  from ..schema import TrainerCallback
  from ..constants import PT_PREFIX
  from ..constants import SCORES_FILE
label_desc: Use image node_id 2 for calling the _LogMetricsMsgCallback obj's underlying member method code with example usage: obj._step_str(state) and returns: str, current_step, str, total_step, str