code: def extension_extract_fn(pathname):
      ext = os.path.splitext(pathname)[1]
      # Remove dot
      if ext:
          ext = ext[1:]
      return ext
  
imports: import io
  import json
  import os.path
  import pickle
  import tempfile
  import torch
  from torch.utils.data.datapipes.utils.common import StreamWrapper
label_desc: Use image node_id 7 for calling a global function with example usage: extension_extract_fn(pathname) and returns: ext