code: def get_cache_dir():
      cachedir = _get_cachedir()
      if cachedir is None:
          raise RuntimeError(
              "Could not find a suitable configuration directory"
          )
      cache_dir = os.path.join(cachedir, "test_cache")
      if not os.path.exists(cache_dir):
          try:
              cbook.mkdirs(cache_dir)
          except IOError:
              return None
      if not os.access(cache_dir, os.W_OK):
          return None
      return cache_dir
  
imports: from __future__ import absolute_import, division, print_function
  import six
  import atexit
  import functools
  import hashlib
  import itertools
  import os
  import re
  import shutil
  import sys
  from tempfile import TemporaryFile
  import numpy
  import matplotlib
  from matplotlib.compat import subprocess
  from matplotlib.testing.exceptions import ImageComparisonFailure
  from matplotlib import _png
  from matplotlib import _get_cachedir
  from matplotlib import cbook
label_desc: Use image node_id 3 for calling a global function with example usage: get_cache_dir() and returns: cache_dir, None, None