code: def _validate_nested_persisted_tensors(persisted_tensors):
      """Raises a ValueError when a nested dict is empty in persisted_tensors."""
  
      for key, entry in persisted_tensors.items():
          if not isinstance(entry, dict):
              continue
          if not entry:
              raise ValueError(
                  "Got empty nested dictionary for key: '{}'".format(
                      key
                  )
              )
          _validate_nested_persisted_tensors(entry)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import abc
  import collections
  import six
label_desc: Use image node_id 1 for calling a global function with example usage: _validate_nested_persisted_tensors(persisted_tensors) without return types