code: def _check_n_cache_threads_running():
      """Return how many threads have the name 'PyFFTWCacheThread.
  
      Obviously, this isn't production quality, but it should suffice for
      the tests here.
      """
  
      cache_threads = 0
      for each_thread in threading.enumerate():
          if each_thread.name == "PyFFTWCacheThread":
              cache_threads += 1
  
      return cache_threads
  
imports: import copy
  import sys
  from pyfftw import interfaces, builders
  import pyfftw
  import numpy
  import numpy
  import unittest
  from .test_pyfftw_base import run_test_suites, miss
  from .test_pyfftw_numpy_interface import InterfacesNumpyFFTTestFFT
  import threading
  import time
  import os
  import hashlib
label_desc: Use image node_id 1 for calling a global function with example usage: _check_n_cache_threads_running() and returns: cache_threads