code: def test_forward_shape(self):
      layer = tl.BatchNorm()
      x = np.ones((30, 20, 70)).astype(np.float32)
      _, _ = layer.init(shapes.signature(x))
      y = layer(x)
      self.assertEqual(y.shape, x.shape)
  
file_path: trax/trax/layers/normalization_test.py
imports: from absl.testing import absltest
  from absl.testing import parameterized
  import numpy
  from trax import fastmath
  from trax import shapes
  import trax.layers
label_desc: Use image node_id 1 for calling the BatchNormTest obj's underlying member method code with example usage: obj.test_forward_shape() without return types