code: def test_forward_dtype(self, backend, dtype):
      with fastmath.use_backend(backend):
          layer = tl.LayerNorm()
          x = np.ones((3, 2, 7)).astype(dtype)
          _, _ = layer.init(shapes.signature(x))
          y = layer(x)
          self.assertEqual(y.dtype, dtype)
  
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 2 for calling the LayerNormTest obj's underlying member method code with example usage: obj.test_forward_dtype(backend, dtype) without return types