docstr: Finds the filepath of latest saved checkpoint file.
  :param dirname: directory where the checkpoints were saved
  return: The full path to the latest checkpoint or `None` if no checkpoint was found.
docstr_tok: ["Finds","the","filepath","of","latest","saved","checkpoint","file",".",":","param","dirname",":","directory","where","the","checkpoints","were","saved","return",":","The","full","path","to","the","latest","checkpoint","or","`","None","`","if","no","checkpoint","was","found","."]
code: def get_latest_checkpoint(cls, dirname):
      """
      Finds the filepath of latest saved checkpoint file.
      :param dirname: directory where the checkpoints were saved
      return: The full path to the latest checkpoint or `None` if no checkpoint was found.
      """
      ckpt_path = cls._format_checkpoint_name(
          dirname, filename=cls.CHECKPOINT_NAME_LAST
      )
      from bigdl.orca.data.file import exists
  
      if not exists(ckpt_path):
          invalidInputError(
              False, f"Latest checkpoint at {ckpt_path} not found."
          )
      return ckpt_path
  
file_path: BigDL/python/orca/src/bigdl/orca/learn/pytorch/callbacks/model_checkpoint.py
imports: from bigdl.orca.learn.pytorch.callbacks import Callback
  import os
  import re
  import warnings
  from bigdl.dllib.utils.log4Error import invalidInputError
label_desc: Use image node_id 6 for calling the ModelCheckpoint obj's underlying member method code with example usage: obj.get_latest_checkpoint(cls, dirname) and returns: ckpt_path