code: def testAllreduceFallback(self):
      self.RunningAllreduceWithGPUs(
          list(range(workspace.NumGpuDevices())), muji.AllreduceFallback
      )
  
file_path: pytorch/caffe2/python/muji_test.py
imports: import numpy
  import unittest
  from caffe2.python import core, workspace, muji, test_util
label_desc: Use image node_id 2 for calling the TestMuji obj's underlying member method code with example usage: obj.testAllreduceFallback() without return types