code: def input_layer(self):
      from lasagne.layers import InputLayer
  
      return InputLayer((2, 3, 4, 5))
  
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 2 for calling the TestExpressionLayer obj's underlying member method code with example usage: obj.input_layer() and returns: InputLayer