code: def test_switchsparse_ff_train(self):
      d_model = 1024
      n_experts = 64
      d_ff = d_model * 8
      x_shape = (3, 7, d_model)
      layer = sparsity.SwitchSparseFF(
          d_ff=d_ff, n_experts=n_experts, mode="train"
      )
      x = np.ones(x_shape).astype(np.float32)
      layer.init(shapes.signature(x))
      y = layer(x)
      self.assertEqual(y.shape, x.shape)
  
imports: import functools
  from absl.testing import parameterized
  import jax
  import numpy
  from tensorflow import test
  from trax import fastmath
  from trax import shapes
  import trax.layers
  from trax.layers import test_utils
  from trax.layers.research import sparsity
label_desc: Use image node_id 7 for calling the EfficientFeedForwardTest obj's underlying member method code with example usage: obj.test_switchsparse_ff_train() without return types