code: def layer(self, layer_vars):
      return layer_vars["layer"]
  
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 3 for calling the TestNonlinearityLayer obj's underlying member method code with example usage: obj.layer(layer_vars) and returns: layer_vars