code: def get_caller(stack_index=2, root_dir=None):
      # pylint: disable=g-doc-args
      """Returns file.py:lineno of your caller.
  
      A stack_index of 2 will provide
          the caller of the function calling this function. Notice that stack_index
          of 2 or more will fail if called from global scope.
      """
      caller = inspect.getframeinfo(inspect.stack()[stack_index][0])
  
      # Trim the filenames for readability.
      filename = caller.filename
      if root_dir is not None:
          filename = re.sub("^" + root_dir + "/", "", filename)
      return "%s:%d" % (filename, caller.lineno)
  
file_path: tensor2tensor/tensor2tensor/utils/mlperf_log.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import inspect
  import json
  import logging
  import os
  import re
  import sys
  import time
  import uuid
  from tensor2tensor.utils.mlperf_tags import *
label_desc: Use image node_id 2 for calling a global function with example usage: get_caller(stack_index, root_dir) and returns: unknown