code: def test_weights_state(self):
      layer = tl.Fn(
          "2in2out",
          lambda x, y: (x + y, jnp.concatenate([x, y], axis=0)),
          n_out=2,
      )
      layer.init_weights_and_state(None)
      self.assertEmpty(layer.weights)
      self.assertEmpty(layer.state)
  
imports: from absl.testing import absltest
  from absl.testing import parameterized
  import numpy
  from trax import fastmath
  from trax import shapes
  from trax.fastmath import numpy
  import trax.layers
label_desc: Use image node_id 5 for calling the FnTest obj's underlying member method code with example usage: obj.test_weights_state() without return types