class_docstr: Used to save a checkpoint on exception.
  
  Args:
      dirpath: directory to save the checkpoint file.
      filename: checkpoint filename. This must not include the extension.
  
  Raises:
      ValueError:
          If ``filename`` is empty.
  
  
  Example:
      >>> from lightning.pytorch import Trainer
      >>> from lightning.pytorch.callbacks import OnExceptionCheckpoint
      >>> trainer = Trainer(callbacks=[OnExceptionCheckpoint(".")])
code: def ckpt_path(self) -> str:
      return os.path.join(
          self.dirpath, self.filename + self.FILE_EXTENSION
      )
  
file_path: pytorch-lightning/src/lightning/pytorch/callbacks/on_exception_checkpoint.py
imports: import os
  from typing import Any
  from typing_extensions import override
  import lightning.pytorch
  from lightning.fabric.utilities.types import _PATH
  from lightning.pytorch.callbacks import Checkpoint
label_desc: Use image node_id 2 for calling the OnExceptionCheckpoint obj's underlying member method code with example usage: obj.ckpt_path() and returns: os