code: def slot_variable_key(variable_path, optimizer_path, slot_name):
      """Returns checkpoint key for a slot variable."""
      # Name slot variables:
      #
      #   <variable name>/<_OPTIMIZER_SLOTS_NAME>/<optimizer path>/<slot name>
      #
      # where <variable name> is exactly the checkpoint name used for the original
      # variable, including the path from the checkpoint root and the local name in
      # the object which owns it. Note that we only save slot variables if the
      # variable it's slotting for is also being saved.
  
      return (
          f"{variable_path}/{_OPTIMIZER_SLOTS_NAME}/{optimizer_path}/"
          f"{escape_local_name(slot_name)}"
      )
  
file_path: tensorflow-upstream/tensorflow/python/trackable/trackable_utils.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import collections
label_desc: Use image node_id 8 for calling a global function with example usage: slot_variable_key(variable_path, optimizer_path, slot_name) and returns: variable_path, str, _OPTIMIZER_SLOTS_NAME, str, optimizer_path, str, escape_local_name