code: def _prefix_metric_keys(
      metrics_dict: Dict[str, float], prefix: str, separator: str
  ) -> Dict[str, float]:
      return {
          prefix + separator + k: v for k, v in metrics_dict.items()
      }
  
file_path: pytorch-lightning/src/lightning/pytorch/callbacks/device_stats_monitor.py
imports: from typing import Any, Dict, Optional
  from typing_extensions import override
  import lightning.pytorch
  from lightning.pytorch.accelerators.cpu import _PSUTIL_AVAILABLE
  from lightning.pytorch.callbacks.callback import Callback
  from lightning.pytorch.utilities.exceptions import MisconfigurationException
  from lightning.pytorch.utilities.types import STEP_OUTPUT
label_desc: Use image node_id 1 for calling a global function with example usage: _prefix_metric_keys(metrics_dict, prefix, separator) and returns: unknown