code: def backend_cpu64(request):
      """
      Fixture that returns a cpu backend using 64 bit dtype.
      For use in tests like gradient checking whihch need higher
      precision
      """
      be = get_backend(request, datatype=np.float64)
  
      # add a cleanup call - will run after all tests in module are done
      def cleanup():
          be = request.getfuncargvalue("backend_cpu64")
          del be
  
      request.addfinalizer(cleanup)
  
      # tests using this fixture can access the backend object from
      # backend or use the NervanaObject.be global
      return be
  
imports: import itertools
  import numpy
  import pytest
  import re
  import os
  import sys
  from neon.backends import gen_backend
  from neon.backends.nervanacpu import NervanaCPU
  from neon.layers.container import DeltasTree
label_desc: Use image node_id 8 for calling a global function with example usage: backend_cpu64(request) and returns: be