code: def testShapeInferencePow(self):
      model = model_helper.ModelHelper(name="powtest")
      model.Pow("x", "y", exponent=-1.0)
      workspace.FeedBlob(
          "x", np.random.rand(1, 2, 3, 4).astype(np.float32)
      )
      self.InferTensorRunAndCompare(model)
  
imports: import numpy
  import unittest
  from caffe2.proto import caffe2_pb2
  from caffe2.python import core, workspace, test_util, model_helper, brew, build
label_desc: Use image node_id 27 for calling the TestShapeInference obj's underlying member method code with example usage: obj.testShapeInferencePow() without return types