code: def crop_layer(self):
      from lasagne.layers.merge import ElemwiseSumLayer
  
      return ElemwiseSumLayer(
          [Mock(), Mock()], coeffs=[2, -1], cropping=["lower"] * 2
      )
  
imports: from mock import Mock
  import numpy
  import pytest
  import theano
label_desc: Use image node_id 2 for calling the TestElemwiseSumLayer obj's underlying member method code with example usage: obj.crop_layer() and returns: ElemwiseSumLayer