code: def default_filename_fcn(x: Union[str, int]) -> str:
      return f"model_{x}.pt"
  
file_path: kornia/kornia/x/callbacks.py
imports: from pathlib import Path
  from typing import Callable, Dict, Optional, Union
  import torch
  from kornia.core import Module
  from kornia.metrics import AverageMeter
  from .utils import TrainerState
label_desc: Use image node_id 1 for calling a global function with example usage: default_filename_fcn(x) and returns: str, x, str