code: def _test_simple_imputer(self, model, data, backend):
      model.fit(data)
  
      hb_model = hummingbird.ml.convert(model, backend, data)
  
      self.assertIsNotNone(hb_model)
      np.testing.assert_allclose(
          model.transform(data),
          hb_model.transform(data),
          rtol=1e-06,
          atol=1e-06,
      )
  
imports: import unittest
  import warnings
  import numpy
  import torch
  from sklearn.impute import MissingIndicator, SimpleImputer
  from hummingbird.ml._utils import onnx_runtime_installed, tvm_installed
  import hummingbird.ml
label_desc: Use image node_id 1 for calling the TestSklearnSimpleImputer obj's underlying member method code with example usage: obj._test_simple_imputer(model, data, backend) without return types