code: def _get_backing_memmap(a):
      """Recursively look up the original np.memmap instance base if any."""
      b = getattr(a, "base", None)
      if b is None:
          # TODO: check scipy sparse datastructure if scipy is installed
          # a nor its descendants do not have a memmap base
          return None
  
      elif isinstance(b, mmap):
          # a is already a real memmap instance.
          return a
  
      else:
          # Recursive exploration of the base ancestry
          return _get_backing_memmap(b)
  
imports: from mmap import mmap
  import errno
  import os
  import stat
  import threading
  import atexit
  import tempfile
  import time
  import warnings
  import weakref
  from uuid import uuid4
  from multiprocessing import util
  from pickle import whichmodule, loads, dumps, HIGHEST_PROTOCOL, PicklingError
  from .numpy_pickle import dump, load, load_temporary_memmap
  from .backports import make_memmap
  from .disk import delete_folder
  from .externals.loky.backend import resource_tracker
label_desc: Use image node_id 4 for calling a global function with example usage: _get_backing_memmap(a) and returns: None, a, _get_backing_memmap