code: def default_ccache_dir() -> str:
      """:return: ccache directory for the current platform"""
      # Share ccache across containers
      if "CCACHE_DIR" in os.environ:
          ccache_dir = os.path.realpath(os.environ["CCACHE_DIR"])
          try:
              os.makedirs(ccache_dir, exist_ok=True)
              return ccache_dir
          except PermissionError:
              logging.info(
                  "Unable to make dirs at %s, falling back to local temp dir",
                  ccache_dir,
              )
      # In osx tmpdir is not mountable by default
      import platform
  
      if platform.system() == "Darwin":
          ccache_dir = "/tmp/_mxnet_ccache"
          os.makedirs(ccache_dir, exist_ok=True)
          return ccache_dir
      return os.path.join(os.path.expanduser("~"), ".ccache")
  
file_path: mxnet/ci/build.py
imports: import argparse
  import pprint
  import os
  import signal
  import subprocess
  from itertools import chain
  from subprocess import check_call
  from typing import *
  import yaml
  from util import *
label_desc: Use image node_id 5 for calling a global function with example usage: default_ccache_dir() and returns: os, ccache_dir, ccache_dir