code: def test_init_none_nonlinearity(
      self, NonlinearityLayer, dummy_input_layer
  ):
      import lasagne.nonlinearities
  
      layer = NonlinearityLayer(
          dummy_input_layer,
          nonlinearity=None,
      )
      assert layer.nonlinearity == lasagne.nonlinearities.identity
  
imports: from mock import Mock
  import numpy
  import pytest
  import theano
  from lasagne.layers import InputLayer, standardize, get_output, get_all_params
  from lasagne.utils import floatX
label_desc: Use image node_id 4 for calling the TestNonlinearityLayer obj's underlying member method code with example usage: obj.test_init_none_nonlinearity(NonlinearityLayer, dummy_input_layer) without return types