code: def test_bad_coeffs_fails(self, layer):
      from lasagne.layers.merge import ElemwiseSumLayer
  
      with pytest.raises(ValueError):
          ElemwiseSumLayer([Mock(), Mock()], coeffs=[2, 3, -1])
  
imports: from mock import Mock
  import numpy
  import pytest
  import theano
label_desc: Use image node_id 6 for calling the TestElemwiseSumLayer obj's underlying member method code with example usage: obj.test_bad_coeffs_fails(layer) without return types