code: def flatten_dict(d: dict, parent_key="", sep="_"):
      """
      Flattens a dict, delimited with a '_'. For example the input:
      {
          'top_1': {
              'res_5': 100
          }
      }
  
      will return:
  
      {
          'top_1_res_5': 100
      }
      """
      items = []
      for k, v in d.items():
          new_key = parent_key + sep + k if parent_key else k
          if isinstance(v, collections.abc.MutableMapping):
              items.extend(flatten_dict(v, new_key, sep=sep).items())
          else:
              items.append((new_key, v))
      return dict(items)
  
imports: import collections
  import collections.abc
  import logging
  import os
  import random
  import sys
  import tempfile
  import time
  from functools import partial, wraps
  from typing import Tuple
  import numpy
  import pkg_resources
  import torch
  import torch.multiprocessing
  from iopath.common.file_io import g_pathmgr
  from scipy.sparse import csr_matrix
  from vissl.utils.extract_features_utils import ExtractedFeaturesLoader
label_desc: Use image node_id 19 for calling a global function with example usage: flatten_dict(d, parent_key, sep) and returns: dict